Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Engineering Physics

First Advisor

Yung Kee Yeo, PhD.


In order to fully utilize newly developed Ge1-ySny and Ge1-x-ySixSny materials for new novel optoelectronic devices, the optical and electrical properties of these alloys 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 performed to determine the properties of the epilayers alone. Reasonable results for the average volume carrier density in the lm were obtained. It was also found that there exists high level of surface states at the surface of almost all the samples. These studies should be very useful for the development of practical devices based on Ge1-ySny alloys.

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