PGI-9 – Halbleiter-Nanoelektronik
Area of research:
Diploma & Master Thesis
Contract time limit:
Background:Silicon (Si), which underpins the whole digital world of electronics, lacks the prime capability for efficient optoelectronics, the direct bandgap. The recent prove of a direct bandgap in an all-group IV germanium tin alloy (GeSn) has fueled the prospect of optoelectronic components. Furthermore, first electrical investigations of the new material showed higher carrier mobilities, making them also promising for channel material in future field-effect transistors (FET). Incorporation of Si for the formation of ternary SiGeSn alloys allows engineering of the material’s bandstructure, which is important especially for heterostructures, in which carriers can be efficiently held inside active regions.
An important building block of future devices are the formation of electrical contacts. While some work has been devoted to investigation of contact formation by alloying GeSn with nickel (Ni), no such work has been performed for SiGeSn ternaries yet..
Project description:The candidate will perform several structural and electrical characterization techniques. SiGeSn ternaries of different compositions, both intrinsic, n- and p-type, are investigated after growth in a reduced-pressure CVD reactor at the same institute
The work involves sample preparation for electrical characterizations in the Helmholtz Nano Facility (HNF) clean rooms. Deposition and formation of metal contacts are investigated, with special care regarding the severe thermal budget constraints of the Sn-based material system. Understanding of the electrical contact behavior should be gained by investigation of Schottky barrier heights, for different types of samples. Further techniques for optimizing the electrical contacts, such as dopant segregation will be investigated..