|Student Name:||Thomas Harris, CTR|
|Thesis:||A SYSTEMATIC STUDY OF THE OPTICAL AND ELECTRICAL PROPERTIES OF Ge(1-y)Sn(y) AND Ge(1-x-y)Si(x)Sn(y) SEMICONDUCTORS|
|Location:||Bldg 640, Rm 353|
|Date & Time:||02/04/2014 at 1030|
|Abstract:|| In order to fully utilize newly developed semiconductors such as Ge1-ySny and Ge1-x-ySixSny alloys in new novel optoelectronic devices, the optical and electrical properties of these materials were investigated using photoluminescence (PL) and Hall-effect measurements. Direct bandgap PL emission was observed from almost all the samples, making them very promising candidates for Si-based light emitting devices. T-dependent PL studies also indicate that the indirect-to-direct bandgap transition of Ge1-ySny alloys might take place at a much lower Sn content than the theory predicts. T-dependent Hall-effect measurements showed both degenerate parallel conducting layers as well as a conductivity type change from p to n at around 370-435 K, which could affect the operation of devices made from these materials. Etch studies were also performed to determine the properties of the epilayers alone. Reasonable results for the average volume carrier density in the film were obtained. It was also found that there exists high level of surface states at the surface of almost all the samples. In conclusion, these studies should be very useful for the development of practical devices based on Ge1-ySny alloys.