Atomic layer deposition - building surfaces by atom by atom
Imagine being able to build surfaces with atomic precision. The atomic layer deposition (ALD) technique can provide such control by depositing monolayers of compounds in a sequential manner.
The ALD technique builds new surfaces by exploiting self-limiting reactions between highly reactive gas molecules and active sites on surfaces. The self-limiting nature of the process ensures conformal and pin-hole free film on surfaces with complex geometries such as porous supports.
The technique is currently used in large scale for deposition of high-k materials for transistors, enabling the ever shrinking size of such microelectronics. It is also used in corrosion protection - from exposed process equipment to delicate silver jewelry. We exploit the technique in deposition of model materials for studies of catalytic processes since it can provide even distribution of catalytic materials on porous supports, even in the very tiniest pores.
The principle behind the technique is to split a chemical reaction between two compounds into a sequential process, where each compound is allowed to saturate a substrate or support in an alternating manner. This strategy provides a digital control of the deposited material in terms of both thickness and composition. We have demonstrated its suitability to deposit materials such as metals, oxides, nitrides, phosphates, organic- inorganic hybrids, and also purely organic compounds. Its potential is huge, both in terms of types of materials, applications, and also possibilities for studying chemical reactions in a detailed manner.