Date of Award

Summer 7-17-2014

Document Type


Degree Name

Doctor of Philosophy (PhD)


Electrical, Computer & Energy Engineering

First Advisor

Bart Van Zeghbroeck

Second Advisor

Garret Moddel

Third Advisor

Wounjhang Park


Incorporating bismuth into epitaxially grown GaAs layers produces the alloy

GaAs1-xBix. This new material system shifts the band gap of GaAs down by approximately 88 meV/%Bi, while maintaining a small lattice mismatch of less than 0.25 % for a 200-300 meV band gap shift. This material has many potential applications in optical and electron devices. In this work the material is studied for use in device applications, specifically heterojunction bipolar transistors with a narrow band gap GaAsBi base layer. The performance of this device is simulated to find its maximum potential gain and frequency of operation in the X-band at devices sizes of 0.5 μm for < 2.5 % bismuth alloying. P-N and HBT devices are fabricated to characterize material quality and HBT performance. Loss mechanisms are studied to improve future devices in the GaAsBi material system.