QuTe QUantum emitters in semiconductors for future TEchnologies

• Ousdal, Erlend Lemva; Bathen, Marianne Etzelmüller; Medeiros, Helton Goncalves de; Galeckas, Augustinas; Kumar, Piyush & Martins, Maria I.M. [Vis alle 10 forfattere av denne artikkelen] (2026). Control and tuning of color centers in 4H silicon carbide by application of electric field via Schottky diode. Materials Science in Semiconductor Processing. ISSN 1369-8001. 201. doi: 10.1016/j.mssp.2025.110097. Fulltekst i vitenarkiv Vis sammendrag

  The ability to tune and manipulate the energy and intensity of photons emitted from color centers in semiconductors is of great importance for developing point defect quantum emitters as a platform for future quantum technology (QT) applications. One of the promising materials to realize point defect based QT is silicon carbide (SiC), as it combines a plethora of color center candidates with mature material processing and device fabrication. Here we explore the use of a Schottky diode, fabricated on a highly doped n-type 4H-SiC epitaxial layer, to control and modulate defect-related emission under both forward and reverse bias conditions. Zero phonon lines (ZPLs) from three prominent color centers are investigated: V1, V1’ and V2 assigned to the silicon vacancy, B1 and B2 from the carbon antisite-vacancy pair, and PL4 of the divacancy complex. All the studied defect-related emission wavelengths are found to shift in response to applied bias, but with a varying magnitude and direction of the shift. The electric field-induced variations are assigned to Stark effect and current flow within the device. Furthermore, two unknown defect signatures, labeled K1 and K2, are observed in the vicinity (within 2 meV) of the V2 ZPL and exhibit a strong forward bias dependence. A possible origin related to silicon vacancies perturbed by nearby carbon antisites is discussed.

• Ousdal, Erlend Lemva; Ghezellou, Misagh; Ul-Hassan, Jawad; Kuznetsov, Andrej; Vines, Lasse & Bathen, Marianne Etzelmüller (2025). Identification of electrically active defects in 6⁢𝐻-SiC. PHYSICAL REVIEW MATERIALS. 9(12). doi: 10.1103/qzfw-162p. Fulltekst i vitenarkiv Vis sammendrag

  Deep level defects in silicon carbide (SiC) are of great importance for developing both power electronics and quantum technology applications based on SiC material. While the more technologically mature 4⁢𝐻 polytype has been widely explored, electrical identification of deep level defect states in 6⁢𝐻 -SiC has not been completed. This work aims to identify irradiation-induced charge state transition levels arising from intrinsic defects in 6⁢𝐻 -SiC using deep level transient spectroscopy (DLTS) and the formation energy diagram formalism based on density functional theory (DFT) calculations. By comparing experimental results of 6⁢𝐻 -SiC epitaxial layers with measurements of 4⁢𝐻 -SiC material that has been grown under identical conditions, combined with DFT calculations, we assign possible origins for the observed DLTS-signatures.

• Turiansky, Mark E.; Mu, Sai; Razinkovas, Lukas; Parto, Kamyar; Patel, Sahil D. & Doan, Sean [Vis alle 11 forfattere av denne artikkelen] (2025). Characterization of chromium impurities in β‐Ga2O3. Journal of Applied Physics. ISSN 0021-8979. 137(10). doi: 10.1063/5.0255859. Fulltekst i vitenarkiv Vis sammendrag

  Chromium is a common transition-metal impurity that is easily incorporated during crystal growth. It is perhaps best known for giving rise to the 694.3 nm (1.786 eV) emission in Cr-doped Al2O3⁠, exploited in ruby lasers. Chromium has also been found in monoclinic gallium oxide, a wide-bandgap semiconductor being pursued for power electronics. In this work, we thoroughly characterize the behavior of Cr in Ga2O3 through theoretical and experimental techniques. β-Ga2O3 samples are grown with the floating zone method and show evidence of a sharp photoluminescence signal, reminiscent of ruby. We calculate the energetics of formation of Cr from first principles, demonstrating that Cr preferentially incorporates as a neutral impurity on the octahedral site. Cr possesses a quartet ground-state spin and has an internal transition with a zero-phonon line near 1.8 eV. By comparing the calculated and experimentally measured luminescence lineshape function, we elucidate the role of coupling to phonons and uncover features beyond the Franck–Condon approximation. The combination of strong emission with a small Huang–Rhys factor of 0.05 and a technologically relevant host material renders Cr in Ga2O3 attractive as a quantum defect.

• Samperi, Orazio; Azarov, Alexander; Bobal, Viktor; Bertolini, Mario Pietro; Cantiano, Massimiliano & Vines, Lasse [Vis alle 9 forfattere av denne artikkelen] (2025). Effects of ion channelling on 350 keV proton implantation of 4H-SiC measured by D-SIMS and DLTS defect profiling. Materials Science in Semiconductor Processing. ISSN 1369-8001. 190. doi: 10.1016/j.mssp.2025.109320. Fulltekst i vitenarkiv
• Silkinis, Rokas; Maciaszek, Marek; Žalandauskas, Vytautas; Bathen, Marianne Etzelmüller; Vines, Lasse & Alkauskas, Audrius [Vis alle 7 forfattere av denne artikkelen] (2025). Optical lineshapes of the C center in silicon from ab initio calculations: Interplay of localized modes and bulk phonons. Physical review B (PRB). ISSN 2469-9950. 111(12). doi: 10.1103/PhysRevB.111.125136. Fulltekst i vitenarkiv
• Herklotz, F.; Chaplygin, I.; Lavrov, E.V.; Melnikov, V.V.; Galazka, Z. & Vines, Lasse (2025). Transition metal-hydrogen complexes in SnO2. Physical review B (PRB). ISSN 2469-9950. 111(19). doi: 10.1103/PhysRevB.111.195208. Fulltekst i vitenarkiv
• Ghezellou, Misagh; Ousdal, Erlend Lemva; Bathen, Marianne Etzelmüller; Vines, Lasse & Ul-Hassan, Jawad (2025). Influence of different hydrocarbons on impurities and minority carrier lifetime in 4H-SiC epitaxial layers. JPhys Materials. 8, s. 1–12. doi: 10.1088/2515-7639/adb7c0. Fulltekst i vitenarkiv Vis sammendrag

  This study explores the influence of different hydrocarbons, methane and propane, on the properties of 4H-SiC epitaxial layers grown by chloride-based chemical vapor deposition. By systematically varying the C/Si and N/C ratios during epitaxial growth, and employing a comprehensive suite of characterization techniques, a better understanding of how growth conditions influence material properties is gained. We show that the n-type dopant incorporation strongly depends on the choice of hydrocarbon especially at lower doping levels. Furthermore, we have observed that methane contributes to a relatively longer carrier lifetime value compared to propane, though a similar lifetime limiting carbon vacancy defect concentration has been observed for both hydrocarbons in as-grown epitaxial layers. Moreover, additional defect levels are also suggested by deep-level transient spectroscopy, potentially related to chlorine complexes, with varying concentrations depending on the choice of hydrocarbon and C/Si ratio. These observations offer insights into the complicated interplay of factors influencing doping, minority carrier lifetime, and defect formation in 4H-SiC epitaxial layers during the epitaxial growth process, and contribute to the optimization of growth parameters depending on the application in question.

• Martinella, Corinna; Bathen, Marianne Etzelmüller; Galeckas, Augustinas & Grossner, Ulrike (2025). Formation of extended defects in heavy-ion-degraded SiC power MOSFETs. APL Materials. 13(5). doi: 10.1063/5.0258995. Fulltekst i vitenarkiv Vis sammendrag

  Silicon carbide (SiC) power devices offer distinct advantages over silicon-based technology and are envisioned to be of great benefit also for space applications. However, their reliability in space is reduced due to the high susceptibility to space-radiation, where single event effects (SEEs) induced by heavy ions are a particular risk. This work focuses on identifying the microscopic origin of a specific non-destructive SEE in SiC power MOSFETs known as single event leakage current (SELC), characterized by a permanent degradation of the gate and drain leakage currents and observed at a relatively low blocking voltage during heavy-ion exposure. The effect investigated is categorized as SELC II, and devices exposed to both broad-beam and microbeam of heavy-ions are studied herein. Using imaging photoluminescence spectroscopy, we observe distinct bright-spots after heavy-ion irradiation, containing spectral features that indicate the formation of stacking faults during exposure and subsequent biasing.

• Houam, Sirine; Ouaddah, Hadjer; Regula, Gabrielle; Périchaud, Isabelle; Reinhart, Guillaume & Sabatino, Marisa Di [Vis alle 12 forfattere av denne artikkelen] (2025). A method to relate the presence of structural defects and impurities and their impact on the electrical activity in silicon for photovoltaic applications. Solar Energy Materials and Solar Cells. ISSN 0927-0248. 282. doi: 10.1016/j.solmat.2025.113415. Fulltekst i vitenarkiv
• Hommedal, Ylva Knausgård; Bathen, Marianne Etzelmüller; Reinertsen, Vilde Mari; Johansen, Klaus Magnus H; Vines, Lasse & Frodason, Ymir Kalmann (2024). Theoretical modeling of defect diffusion in wide bandgap semiconductors. Journal of Applied Physics. ISSN 0021-8979. 135. doi: 10.1063/5.0205866. Fulltekst i vitenarkiv Vis sammendrag

  Since the 1940s, it has been known that diffusion in crystalline solids occurs due to lattice defects. The diffusion of defects can have a great impact on the processing and heat treatment of materials as the microstructural changes caused by diffusion can influence the material qualities and properties. It is, therefore, vital to be able to control the diffusion. This implies that we need a deep understanding of the interactions between impurities, matrix atoms, and intrinsic defects. The role of density functional theory (DFT) calculations in solid-state diffusion studies has become considerable. The main parameters to obtain in defect diffusion studies with DFT are formation energies, binding energies, and migration barriers. In particular, the utilization of the nudged elastic band and the dimer methods has improved the accuracy of these parameters. In systematic diffusion studies, the combination of experimentally obtained results and theoretical predictions can reveal information about the atomic diffusion processes. The combination of the theoretical predictions and the experimental results gives a unique opportunity to compare parameters found from the different methods and gain knowledge about atomic migration. In this Perspective paper, we present case studies on defect diffusion in wide bandgap semiconductors. The case studies cover examples from the three diffusion models: free diffusion, trap-limited diffusion, and reaction diffusion. We focus on the role of DFT in these studies combined with results obtained with the experimental techniques secondary ion mass spectrometry and deep-level transient spectroscopy combined with diffusion simulations.

• Bathen, Marianne Etzelmüller; Kumar, Piyush; Ghezellou, Misagh; Belanche, Manuel; Vines, Lasse & Ul-Hassan, Jawad [Vis alle 7 forfattere av denne artikkelen] (2024). Dual configuration of shallow acceptor levels in 4H-SiC. Materials Science in Semiconductor Processing. ISSN 1369-8001. 177. doi: 10.1016/j.mssp.2024.108360. Fulltekst i vitenarkiv Vis sammendrag

  Acceptor dopants in 4H-SiC exhibit energy levels that are located deeper in the band gap than the thermal energy at room temperature (RT), resulting in incomplete ionization at RT. Therefore, a comprehensive understanding of the defect energetics and how the impurities are introduced into the material is imperative. Herein, we study impurity related defect levels in 4H-SiC epitaxial layers (epi-layers) grown by chemical vapor deposition (CVD) under various conditions using minority carrier transient spectroscopy (MCTS). We find two trap levels assigned to boron impurities, B and D, which are introduced to varying degrees depending on the growth conditions. A second acceptor level that was labeled X in the literature and attributed to impurity related defects is also observed. Importantly, both the B and X levels exhibit fine structure revealed by MCTS measurements. We attribute the fine structure to acceptor impurities at hexagonal and pseudo-cubic lattice sites in 4H-SiC, and tentatively assign the X peak to Al based on experimental findings and density functional theory calculations.

• Zhang, Xie; Turiansky, Mark E.; Razinkovas, Lukas; Maciaszek, Marek; Broqvist, Peter & Yan, Qimin [Vis alle 12 forfattere av denne artikkelen] (2024). First-principles calculations of defects and electron-phonon interactions: Seminal contributions of Audrius Alkauskas to the understanding of recombination processes. Journal of Applied Physics. ISSN 0021-8979. 135(15). doi: 10.1063/5.0205525. Fulltekst i vitenarkiv Vis sammendrag

  First-principles calculations of defects and electron–phonon interactions play a critical role in the design and optimization of materials for electronic and optoelectronic devices. The late Audrius Alkauskas made seminal contributions to developing rigorous first-principles methodologies for the computation of defects and electron–phonon interactions, especially in the context of understanding the fundamental mechanisms of carrier recombination in semiconductors. Alkauskas was also a pioneer in the field of quantum defects, helping to build a first-principles understanding of the prototype nitrogen-vacancy center in diamond, as well as identifying novel defects. Here, we describe the important contributions made by Alkauskas and his collaborators and outline fruitful research directions that Alkauskas would have been keen to pursue. Audrius Alkauskas’ scientific achievements and insights highlighted in this article will inspire and guide future developments and advances in the field.

• Samperi, Orazio; Vines, Lasse; Bertolini, Mario Pietro; Cantiano, Massimiliano; Coffa, Salvo & Fragalà, Maria Elena (2024). Hydrogen depth profiling and multi-energy proton implantation: SIMS as a tool for implant process control. Materials Science in Semiconductor Processing. ISSN 1369-8001. 174. doi: 10.1016/j.mssp.2024.108219. Fulltekst i vitenarkiv
• Ousdal, Erlend Lemva; Bathen, Marianne Etzelmüller; Galeckas, Augustinas; Kuznetsov, Andrej & Vines, Lasse (2024). Formation and stability of point defect color centers in 6H silicon carbide. Journal of Applied Physics. ISSN 0021-8979. 135(22). doi: 10.1063/5.0205832. Fulltekst i vitenarkiv Vis sammendrag

  Point defect color centers acting as single-photon emitters are promising for quantum technology applications and have been extensively studied, e.g., in the 4H polytype of silicon carbide (SiC). However, the physics of such color centers in other SiC polytypes is much less explored. Herein, we study the formation and thermal stability of such color centers in 6H-SiC using photoluminescence spectroscopy. The emissions from typical single-photon emitters, such as silicon vacancies, divacancies, and carbon antisite-vacancy pairs in 6H-SiC, were monitored as a function of the proton irradiation fluence and post-irradiation annealing, and compared to that in 4H-SiC. Overall, at the background of similarities between the emission behavior in 4H- and 6H-SiC polytypes, we observed prominent differences; e.g., for the thermal stability of the carbon antisite-vacancy pair, which exhibited maximized emissions upon 300 and 900  *C anneals in 4H- and 6H-SiC, respectively. Moreover, we observed a range of defect emission signatures not previously reported for 6H-SiC in the literature and discussed their potential origin in the context of the thermal stability. For example, among the PL-lines in 6H-SiC, we detected periodically repeatable emission signatures, resembling the so-called L-lines recently reported in 4H-SiC, even though their exact origin has not yet been settled in the literature. Thus, we use color centers comparison in different polytypes to better understand the nature of the single-photon emitters in SiC.

• Kumar, Piyush; Bathen, Marianne Etzelmüller; Martins, Maria I. M.; Prokscha, Thomas & Grossner, Ulrike (2024). Electrically active defects induced by thermal oxidation and post-oxidation annealing of n-type 4H-SiC. Journal of Applied Physics. ISSN 0021-8979. 135(18). doi: 10.1063/5.0205965. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Karsthof, Robert Michael; Galeckas, Augustinas; Kumar, Piyush; Kuznetsov, Andrej & Grossner, Ulrike [Vis alle 7 forfattere av denne artikkelen] (2024). Impact of carbon injection in 4H-SiC on defect formation and minority carrier lifetime. Materials Science in Semiconductor Processing. ISSN 1369-8001. 176. doi: 10.1016/j.mssp.2024.108316. Fulltekst i vitenarkiv
• Samperi, Orazio; Vines, Lasse; Hallén, Anders & Fragalà, Maria Elena (2024). Charge Carrier Capture by Prominent Defect Centers in 4H-SiC. Defect and Diffusion Forum. ISSN 1012-0386. 434, s. 173–182. doi: 10.4028/p-ls2bVE. Fulltekst i vitenarkiv Vis sammendrag

  The knowledge of capture properties of electrically active defects is of primary importance as it helps to understand which deep states are effective in controlling the excess free carriers’ lifetime. Combining DLTS capture experiments with thermal emission measurements enables an overall thermodynamic description of deep states, thus making it possible to characterize recombination centers in semiconductor-based devices. In the present study, junction DLTS capture rate measurements were employed to extract the true capture cross-sections (inversely proportional to the carrier lifetime) and capture energy barriers for the main lifetime limiting defects in 4H-SiC (silicon carbide). A peculiar forward bias dependence of the capture parameters was observed for the shallow boron (B) hole trap. Capture rate measurements on the deep boron (D-center) trap also evidenced the presence of two capture mechanisms, thus allowing discrimination of D1 and D2 deep states within the D-center DLTS peak. The results were combined with activation energies and apparent capture cross-sections to obtain the free energy (ΔG) of electronic activation for the analysed deep states.

• Hansen, Ethan R.; Niaouris, Vasileios; Matthews, Bethany E.; Zimmermann, Christian; Wang, Xingyi & Kolodka, Roman [Vis alle 9 forfattere av denne artikkelen] (2024). Isolation of Single Donors in ZnO. Physical Review Letters. ISSN 0031-9007. 133(14). doi: 10.1103/PhysRevLett.133.146902. Fulltekst i vitenarkiv
• Sozzi, Giovanna; Sapienza, Sergio; Chiorboli, Giovanni; Vines, Lasse; Hallen, Anders & Nipoti, Roberta (2024). Carrier Lifetime Dependence on Temperature and Proton Irradiation in 4H-SiC Device: An Experimental Law. IEEE Access. 12, s. 74230–74238. doi: 10.1109/ACCESS.2024.3405382. Fulltekst i vitenarkiv Vis sammendrag

  The study focuses on analysing the high-level carrier lifetime ( τHL ) in 4H silicon carbide (4H-SiC) PiN diodes under varying temperatures and proton implantation doses. The objective is to identify an empirical law applicable in technology computer-aided design (TCAD) modelling for SiC devices, describing the dependence of carrier lifetime on temperature to gain insights into how irradiation dose may influence the τHL . We electrically characterize diodes of different diameters subjected to different proton irradiation doses and examine the variations in current-voltage (I-V) and ideality factor (n) curves under various irradiation conditions. The effects of proton irradiation on the epitaxial layer are analysed through capacitance-voltage (C-V) measurements. We correlate the observed effects on I-V, n, and C-V curves to the hypothesis of formation of acceptor-type defects related to carbon vacancies, specifically the Z 1/2 defects generated during the irradiation process. The impact of irradiation on carrier lifetime is investigated by measuring τHL using the open circuit voltage decay (OCVD) technique at different temperatures on diodes exposed to various H+ irradiation doses with constant ion energy. This investigation reveals the presence of a proportional relationship between 1/ τHL and the dose of irradiated protons: the proportionality coefficient, referred to as the damage coefficient (K T ), exhibits an Arrhenius-type dependence on temperature. OCVD-measured lifetime on the various diodes demonstrates a power-law dependence of lifetime on temperature. The exponent of this dependence varies with the irradiation dose, notably showing an increase in temperature dependence at the highest H+ ion dose. This suggests a threshold-like dependence on H+ irradiation dose in the τHL -temperature relationship.

• Ghezellou, Misagh; Kumar, Piyush; Bathen, Marianne E.; Karsthof, Robert Michael; Sveinbjörnsson, Einar Ö. & Grossner, Ulrike [Vis alle 9 forfattere av denne artikkelen] (2023). The role of boron related defects in limiting charge carrier lifetime in 4H-SiC epitaxial layers. APL Materials. 11(3). doi: 10.1063/5.0142415. Fulltekst i vitenarkiv Vis sammendrag

  One of the main challenges in realizing 4H–SiC (silicon carbide)-based bipolar devices is the improvement of minority carrier lifetime in as-grown epitaxial layers. Although Z1/2 has been identified as the dominant carrier lifetime limiting defect, we report on B-related centers being another dominant source of recombination and acting as lifetime limiting defects in 4H–SiC epitaxial layers. Combining time-resolved photoluminescence (TRPL) measurement in near band edge emission and 530 nm, deep level transient spectroscopy, and minority carrier transient spectroscopy (MCTS), it was found that B related deep levels in the lower half of the bandgap are responsible for killing the minority carriers in n-type, 4H–SiC epitaxial layers when the concentration of Z1/2 is already low. The impact of these centers on the charge carrier dynamics is investigated by correlating the MCTS results with temperature-dependent TRPL decay measurements. It is shown that the influence of shallow B acceptors on the minority carrier lifetime becomes neutralized at temperatures above ∼422 K. Instead, the deep B related acceptor level, known as the D-center, remains active until temperatures above ∼570 K. Moreover, a correlation between the deep level concentrations, minority carrier lifetimes, and growth parameters indicates that intentional nitrogen doping hinders the formation of deep B acceptor levels. Furthermore, tuning growth parameters, including growth temperature and C/Si ratio, is shown to be crucial for improving the minority carrier lifetime in as-grown 4H–SiC epitaxial layers.

• Bathen, Marianne Etzelmüller; Selnesaunet, Gard Momrak; Enga, Marius; Kjeldby, Snorre Braathen; Müting, Johanna & Vines, Lasse [Vis alle 7 forfattere av denne artikkelen] (2023). Charge State Control Over Point Defects in SiC Devices. Defect and Diffusion Forum. ISSN 1012-0386. 425, s. 35–42. doi: 10.4028/p-6ho92o. Fulltekst i vitenarkiv Vis sammendrag

  Point defects in silicon carbide (SiC) are well positioned for integration with SiC based quantum photonic devices due to the maturity of SiC material and fabrication technology, the plethora of candidate quantum emitters that can be formed in SiC, and the potential for emission over a wide spectral range from the visible to the infrared. However, for each of the available color centers in SiC, only one of the charge states has displayed quantum emission, meaning that the emission strongly depends on the Fermi level and hence the doping concentration in the material. In this contribution, we discuss the methodology and mechanism for electrical charge-state control over point defects in SiC devices.

• Wang, Xingyi; Zimmermann, Christian; Titze, Michael; Niaouris, Vasileios; Hansen, Ethan R. & D'Ambrosia, Samuel H. [Vis alle 9 forfattere av denne artikkelen] (2023). Properties of Donor Qubits in ZnO Formed by Indium-Ion Implantation. Physical Review Applied. 19(5), s. 054090-1–054090-12. doi: 10.1103/PhysRevApplied.19.054090. Fulltekst i vitenarkiv Vis sammendrag

  Neutral shallow donors (D0) in ZnO have emerged as a promising candidate for solid-state spin qubits. Here we report on the formation of D0 in ZnO via implantation of In and subsequent annealing. The implanted In donors exhibit optical and spin properties on par with those of in situ–doped donors. The inhomogeneous linewidth of the donor-bound-exciton transition is less than 10 GHz, comparable to the optical linewidth of in situ In. Longitudinal spin relaxation times (T1) exceed reported values for in situ Ga donors, indicating that residual In-implantation damage does not degrade T1. Two-laser Raman spectroscopy of the donor spin reveals the hyperfine interaction of the donor electron with the spin-9/2 In nuclei. This work is an important step toward the deterministic formation of In-donor qubits in ZnO with optical access to a long-lived nuclear-spin memory.

• Linnarsson, Margareta; Vines, Lasse & Hallen, Anders (2023). Al Implantation in SiC; Where Will the Ions Come to Rest? Solid State Phenomena. ISSN 1012-0394. 343, s. 57–64. doi: 10.4028/p-nxe4cz. Fulltekst i vitenarkiv Vis sammendrag

  In all implantations into crystalline targets, quite a few ions find a path along a crystal channel or plane, so called channeling, and these ions travel deep into the crystal. This paper treats aluminum (Al) implantation in 4H-SiC and show how the crystal lattice will guide incoming ions deep into the target and modify the final dopant distribution. 4H-SiC samples have been implanted with 100 keV Al-ions, in a “random” direction using the wafer miscut angle of 4°, as well as with the impact beam aligned anti-parallel to the [0001] direction. Aluminium concentration versus depth profiles has been recorded by secondary ion mass spectrometry (SIMS). To track the most probable ion paths during stopping process, SIIMPL, a Monte Carlo simulation code based on the binary collision approximation (MC-BCA) has been used. In addition, the remaining ion energy has been extracted from SIIMPL at various depth along the ion path. Our results show that, independent of the used impact angle, some ions will be steered by crystal planes predominantly into the direction and also along the six directions. The energy loss is smaller along these low index axes. Therefore, at a depth of 1.2 μm, some Al ions along a path may still have kinetic energy, more than 40% of the original 100 keV, and continues to move deep into the SiC sample. The mean projected range of 100 keV ions in 4H-SiC is about 120 nm.

• Serra, Filipe; Gaspar, Guilherme; Viana, Ana; Arumughan, Jayaprasad; Costa, Ivo & Pêra, David [Vis alle 10 forfattere av denne artikkelen] (2023). Gas immersion laser doping: N++ phosphorus doping on p+ Cz-Si wafers with a highly doped p++ emitter. AIP Conference Proceedings. ISSN 0094-243X. 2826. doi: 10.1063/5.0140455. Fulltekst i vitenarkiv
• Dorfer, Christian; Bathen, Marianne Etzelmüller; Race, Salvatore; Kumar, Piyush; Tsibizov, Alexander & Woerle, Judith [Vis alle 7 forfattere av denne artikkelen] (2023). Mapping the impact of defect distributions in silicon carbide devices using the edge transient-current technique. Applied Physics Letters. ISSN 0003-6951. 122. doi: 10.1063/5.0142217. Fulltekst i vitenarkiv
• Kumar, Piyush; Martins, Maria M.; Bathen, Marianne Etzelmüller; Woerle, Judith; Prokscha, Thomas & Grossner, Ulrike (2023). Investigation of the SiO2-SiC Interface Using Low-Energy Muon-Spin-Rotation Spectroscopy. Physical Review Applied. 19. doi: 10.1103/PhysRevApplied.19.054025. Fulltekst i vitenarkiv
• Für, Natalija; Belanche, Manuel; Martinella, Corinna; Kumar, Piyush; Bathen, Marianne Etzelmüller & Grossner, Ulrike (2023). Investigation of Electrically Active Defects in SiC Power Diodes Caused by Heavy Ion Irradiation. IEEE Transactions on Nuclear Science. ISSN 0018-9499. 70(8), s. 1892–1899. doi: 10.1109/TNS.2023.3242760. Fulltekst i vitenarkiv
• Kumar, Piyush; Belanche, Manuel; Für, Natalija; Guzenko, Luka; Woerle, Judith & Bathen, Marianne Etzelmüller [Vis alle 7 forfattere av denne artikkelen] (2023). Energy-Dependent Impact of Proton Irradiation on 4H-SiC Schottky Diodes. Materials Science Forum. ISSN 0255-5476. 1092, s. 187–192. doi: 10.4028/p-0y444y. Fulltekst i vitenarkiv
• Galeckas, Augustinas; Karsthof, Robert Michael; Kingsly, Gana; Kok, Angela; Bathen, Marianne Etzelmüller & Vines, Lasse [Vis alle 7 forfattere av denne artikkelen] (2022). Cross-Sectional Carrier Lifetime Profiling and Deep Level Monitoring in Silicon Carbide Films Exhibiting Variable Carbon Vacancy Concentrations. Physica Status Solidi (a) applications and materials science. ISSN 1862-6300. s. 1–7. doi: 10.1002/pssa.202200449. Fulltekst i vitenarkiv Vis sammendrag

  The carrier lifetime control over 150 μm thick 4H-SiC epitaxial layers via thermal generation and annihilation of carbon vacancy (VC) related Z1/2 lifetime killer sites is reported. The defect developments upon typical SiC processing steps, such as high- and moderate-temperature anneals in the presence of a carbon cap, are monitored by combining electrical characterization techniques capable of VC depth-profiling, capacitance–voltage (CV) and deep-level transient spectroscopy (DLTS), with a novel all-optical approach of cross-sectional carrier lifetime profiling across 4H-SiC epilayer/substrate based on imaging time-resolved photoluminescence (TRPL) spectroscopy in orthogonal pump-probe geometry, which readily exposes in-depth efficacy of defect reduction and surface recombination effects. The lifetime control is realized by initial high-temperature treatment (1800 °C) to increase VC concentration to ≈1013 cm−3 level followed by a moderate-temperature (1500 °C) post-annealing of variable duration under C-rich thermodynamic equilibrium conditions. The post-annealing carried out for 5 h in effect eliminates VC throughout the entire ultra-thick epilayer. The reduction of VC-related Z1/2 sites is proven by a significant lifetime increase from 0.8 to 2.5 μs. The upper limit of lifetimes in terms of carrier surface leakage and the presence of other nonradiative recombination centers besides Z1/2, possibly related to residual impurities such as boron are discussed.

• Assar, Alireza; Martinho, Filipe; Larsen, Jes; Saini, Nishant; Shearer, Denver & Moro, Marcos V. [Vis alle 15 forfattere av denne artikkelen] (2022). Gettering in polySi/SiO xpassivating contacts enables Si-based tandem solar cells with high thermal and contamination resilience. ACS Applied Materials & Interfaces. ISSN 1944-8244. 14(12), s. 14342–14358. doi: 10.1021/acsami.2c00319. Fulltekst i vitenarkiv Vis sammendrag

  Multijunction solar cells in a tandem configuration could further lower the costs of electricity if crystalline Si (c-Si) is used as the bottom cell. However, for direct monolithic integration on c-Si, only a restricted number of top and bottom cell architectures are compatible, due to either epitaxy or high-temperature constraints, where the interface between subcells is subject to a trade-off between transmittance, electrical interconnection, and bottom cell degradation. Using polySi/SiOx passivating contacts for Si, this degradation can be largely circumvented by tuning the polySi/SiOx stacks to promote gettering of contaminants admitted into the Si bottom cell during the top cell synthesis. Applying this concept to the low-cost top cell chalcogenides Cu2ZnSnS4 (CZTS), CuGaSe2 (CGSe), and AgInGaSe2 (AIGSe), fabricated under harsh S or Se atmospheres above 550 °C, we show that increasing the heavily doped polySi layer thickness from 40 to up to 400 nm prevents a reduction in Si carrier lifetime by 1 order of magnitude, with final lifetimes above 500 μs uniformly across areas up to 20 cm2. In all cases, the increased resilience was correlated with a 99.9% reduction in contaminant concentration in the c-Si bulk, provided by the thick polySi layer, which acts as a buried gettering layer in the tandem structure without compromising the Si passivation quality. The Si resilience decreased as AIGSe > CGSe > CZTS, in accordance with the measured Cu contamination profiles and higher annealing temperatures. An efficiency of up to 7% was achieved for a CZTS/Si tandem, where the Si bottom cell is no longer the limiting factor.

• Hebnes, Oliver Lerstøl; Bathen, Marianne Etzelmüller; Schøyen, Øyvind Sigmundson; Winther-Larsen, Sebastian Gregorius; Vines, Lasse & Hjorth-Jensen, Morten (2022). Predicting solid state material platforms for quantum technologies. npj Computational Materials. 8(1). doi: 10.1038/s41524-022-00888-3. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Semiconductor materials provide a compelling platform for quantum technologies (QT). However, identifying promising material hosts among the plethora of candidates is a major challenge. Therefore, we have developed a framework for the automated discovery of semiconductor platforms for QT using material informatics and machine learning methods. Different approaches were implemented to label data for training the supervised machine learning (ML) algorithms logistic regression, decision trees, random forests and gradient boosting. We find that an empirical approach relying exclusively on findings from the literature yields a clear separation between predicted suitable and unsuitable candidates. In contrast to expectations from the literature focusing on band gap and ionic character as important properties for QT compatibility, the ML methods highlight features related to symmetry and crystal structure, including bond length, orientation and radial distribution, as influential when predicting a material as suitable for QT.

• Bathen, Marianne Etzelmüller; Karsthof, Robert Michael; Grossner, Ulrike & Vines, Lasse (2022). Stability, Evolution and Diffusion of Intrinsic Point Defects in 4H-SiC. Materials Science Forum. ISSN 0255-5476. 1062, s. 371–375. doi: 10.4028/p-ryui6b. Fulltekst i vitenarkiv Vis sammendrag

  Silicon carbide (SiC) is a wide band-gap semiconductor of great technological importance, showing promise for application areas ranging from quantum computing and communication to power devices. Vital in both the contexts of power devices and quantum technology is the understanding of intrinsic defects that are introduced during various device processing steps, both immediately after their formation and over the course of defect evolution with temperature. Here we monitor the formation and evolution of intrinsic point defects in n-type 4H-SiC after proton irradiation at room temperature and subsequent annealing in the temperature range 300-1000 °C, and discuss the nature and origin of the EH 4 and EH 5 deep level defects observed by deep level transient spectroscopy around 400-500 K. In particular, the controversy on the nature of the EH5 trap in particular is addressed, where we propose the presence of two overlapping defect peaks: one metastable level that appears after low energy electron irradiation below the silicon displacement limit, and one more stable level that gradually decreases in concentration until an annealing temperature of 1000°C. We argue that the former is likely related to carbon interstitials, while the latter was recently tentatively attributed to the carbon antisite-vacancy pair.

• Karsthof, Robert Michael; Bathen, Marianne Etzelmüller; Kuznetsov, Andrej & Vines, Lasse (2022). Formation of carbon interstitial-related defect levels by thermal injection of carbon into n-type 4H-SiC. Journal of Applied Physics. ISSN 0021-8979. 131. doi: 10.1063/5.0077308. Fulltekst i vitenarkiv Vis sammendrag

  Electrical properties of point defects in 4𝐻-SiC have been studied extensively, but those related to carbon interstitials (Ci) have remained elusive until now. Indeed, when introduced via ion irradiation or implantation, signatures related to Ci observed by deep level transient spectroscopy tend to overlap with those of other primary defects, making the direct identification of Ci-related levels difficult. Recent literature has suggested to assign the so-called M center, often found in as-irradiated 4𝐻-SiC, to charge state transitions of the Ci defect in different configurations. In this work, we have introduced excess carbon into low-doped 𝑛-type 150 𝜇m thick 4𝐻-SiC epilayers by thermal annealing, with a pyrolyzed carbon cap on the sample surface acting as a carbon source. Because the layers exhibited initially low concentrations of carbon vacancies ([𝑉C]=1011cm), this enabled us to study the case of complete VC annihilation and formation of defects due to excess carbon, i.e., carbon interstitials Ci and their higher-order complexes. We report on the occurrence of several new levels upon C injection, which are likely Ci-related. Their properties are different from those found for the M center, which point toward a different microscopic identity of the detected levels. This suggests the existence of a rich variety of Ci-related defects. The study will also help generating new insights into the microscopic process of VC annihilation during carbon injection processes.

Se alle arbeider i NVA

• Bathen, Marianne Etzelmüller; Olsen, Vegard Skiftestad & Vines, Lasse (2024). Hvor går veien? Kvanteteknologiens potensiale i fremtidens teknologi​. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Hebnes, Oliver Lerstøl; Schøyen, Øyvind; Winther-Larsen, Sebastian G.; Vines, Lasse & Hjorth-Jensen, Morten (2024). Predicting solid state material platforms for quantum technologies. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller & Vines, Lasse (2024). Semiconductors as quantum materials - Ongoing research at the LENS group. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Point defects in semiconductors for quantum technologies. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Hvor går veien? Kvanteteknologiens potensiale i fremtidens teknologi. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller & Hjorth-Jensen, Morten (2024). Where are we going? Quantum technology for future applications. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Doping-induced color centers in Silicon Carbide. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Radiation induced defects in SiC Material and Devices ​. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Deltagelse i Abels Tårn. [Radio]. NRK P2. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Hvorfor kvanteteknologi er det mest spennende du kan drive med. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Thermal formation of vacancy-related defects near the ​ SiO2-SiC interface. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Norway’s green quantum future. Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller (2024). Kvanteteknologiens betydning for samfunnsutviklingen. En ny æra? Fulltekst i vitenarkiv
• Bathen, Marianne Etzelmüller; Johnson, Brett C.; Galeckas, Augustinas; martins, maria m; Kumar, Piyush & Silkinis, Rokas [Vis alle 11 forfattere av denne artikkelen] (2023). Doping-induced color centers in silicon carbide ​. Fulltekst i vitenarkiv
• Vines, Lasse; Monakhov, Eduard & Kuznetsov, Andrej (2022). Defects in semiconductors. Journal of Applied Physics. ISSN 0021-8979. 132(15). doi: 10.1063/5.0127714. Fulltekst i vitenarkiv
• Pedersen, Benedicte Allum; Vines, Lasse; Kjeldby, Snorre Braathen & Reinertsen, Vilde Mari (2022). Positioning and control of single-photon emitters in SiC-based nanostructures for quantum applications. Universitetet i Oslo. Fulltekst i vitenarkiv

Se alle arbeider i NVA