Development, testing and simulation of a laser scanning setup for Transient Current Technique (TCT) measurements of silicon radiation detectors.

The Silicon Sensor Technology group at SINTEF MiNaLab has long standing experience in research, development and production of silicon radiation detector in our state-of-the-art clean room facilities.

The aim of this project is to complete the development of a laser scanning setup to be used for Transient Current Technique (TCT) characterisation of silicon radiation detectors [1]. This technique can provide excellent feedback on the operation of silicon detectors in terms of signal efficiency and response uniformity. It is often used to characterise the response of novel silicon sensor designs.

The measurement uses sub-nanosecond laser pulses to generate
free charge carriers into a silicon sensor. The motion of the free
charge carriers induces an electrical signal at the sensor
electrodes that can be collected and processed in different ways: (i) using wideband current transimpedance amplifiers to study the timing evolution of the signal for different hit positions and sensor operating voltages and (ii) using charge amplifiers to estimate the amount of total collected charge for different hit positions. The laser is scanned over the area of interest in 2-dimensional in order to achieve heat maps of the sensor response, aiming at the identification of possible flaws or further improvement in a sensor design.

1. Characterise the operation of the laser driver using laser diodes and propose possible improvements to its design. This task might include PCB design.

2. Develop, refine and document the laser diode coupling procedure to the optical fibre.

3. Write and test the Python code used for positioning of the sensor and for the automatic raster scanning. A basic version of the necessary code is already available but needs to be optimised.

4. Write and test the Python code to acquire the data from the readout electronics and from the oscilloscope.

5. Test the full system using SINTEF silicon detectors.

6. Develop a numerical model for the sensor under test and its interaction with laser pulses using the SYNOPSYS SENTAURUS TCAD tools.

Required qualifications:

1. Basic understanding of semiconductor physics and P-N junction operation
2. Understanding of basic electronics circuits and their behaviour
3. Understanding of basic notions on Printed Circuit Board design and production
4. Basic knowledge of optics and light transport in optical fibres can be useful
5. Good knowledge of the Python programming language:
   • Some of the modules that can be useful are: pyVISA, Matplotlib, scipy, numpy

It is required that the Master project is carried out on-site at SINTEF MiNaLab in Oslo. Supervisor at SINTEF MiNaLAb will be Dr. Marco Povoli.