The Project
The goal of the project is the development of new materials and material combinations with semiconductor properties for use as conductive buffer layers in semiconductor devices. This requires a systematic investigation of material properties using X-ray diffractometry, ellipsometry, Raman scattering, photoluminescence studies, and electrical measurements. The basis of the layers is the sputtering epitaxy process, partially combined with the established method of metalorganic vapor phase epitaxy (MOVPE) for complex Group III nitride device structures. The use of the relatively new sputtering epitaxy technique first enables the realization of transition metal nitride layers and their alloys with conventional Group III nitrides. This is because suitable precursors with sufficiently high vapor pressure for use in MOVPE are available for only a very few transition metals in order to realize sufficient layer thicknesses for investigations. Through this process, many new material combinations are made possible, or the investigation of diverse materials becomes feasible without extreme costs.
Transition metal nitrides can be used as conductive crystalline buffer and cover layers for novel device concepts and also exhibit unexpected properties. As an example, AlScN can be mentioned, which displays ferroelectricity in a larger composition range, thus enabling novel and more powerful transistors.
Through these investigations, the properties of previously uninvestigated materials are to be examined in high crystalline quality to ultimately realize better or entirely new devices that, for example, have lower losses or a larger operating range and can thus save energy, such as in highly efficient voltage converters.