Title:  Silicon-Germanium Heterojunction Bipolar Transistors for High-Temperature and Radiation-Rich Environments

Committee: 

Dr. Cressler, Advisor     

Dr. Shen, Chair

Dr. Lourenco

Abstract:

The objective of this research is to enable the use of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) in high-temperature and radiation-rich environments. The high-temperature electronics market is rapidly growing due to the demand from major sectors such as energy, automotive, and aerospace. This work studies the operation of SiGe HBTs at temperatures as high as 300oC using a silicon-on-insulator (SOI) technology. Preliminary research on characterizing SiGe-on-SOI HBTs at these high temperatures indicate that SiGe HBTs provide adequate DC and AC performance for a variety of analog and RF circuits. Operating any device in extreme environments also requires good understanding of the key reliability degradation mechanisms. The temperature dependence of avalanche generation, Auger recombination, and electrothermal runaway is identified and its effects on the overall safe-operating-area (SOA) of a SiGe HBT technology is explored. The first part of the proposed research is to use the identified SOA temperature trends to build high-temperature-capable circuits. A gate driver circuit with multi-amp current drive aimed at driving large capacitive loads operating at 250oC-300oC is proposed along with several other basic, analog building blocks. The second part of the proposed research is to study the temperature dependence of the single-event effects (SEE) of SiGe HBTs. Deep-space missions to Venus or Jupiter require electronics that can handle both high temperatures and large amounts of radiation. Understanding the role that temperature plays on the radiation effects will help more accurately analyze what a device would experience in actual space environments.