tor with a zinc blende crystal structure. GaAs is used in the manufacturing of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, and infrared light- emitting diodes. GaAs is often used as a substrate material for the epitaxial growth of other III-V semicon- ductors including indium GaAs, aluminum GaAs, and others. The transit frequency is a measure of the intrinsic speed of a transistor and is defined as the frequency where the current gain reduces to one. HBT, a type of bipolar junction transistor (BJT) which uses differing semiconductor materials for the emitter and base regions, creating a heterojunction. BiCMOS is an evolved semiconductor technology that integrates two formerly separate semiconductor tech- nologies, those of the BJT and the CMOS transistor, in a single integrated circuit device. CMOS is a technology for manufacturing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, etc., as well as analog circuits such as image sensors and data converters. Two important characteristics of CMOS devices are high noise immunity and low static power consumption. Since one tran- sistor of the pair is always off, the combination draws significant power only momentarily during switching between ON and OFF states. Consequently, CMOS devices do not dissipate heat as other forms of logic. CMOS also allows a high density of logic functions on a chip. It was primarily for this reason that CMOS became the most used technology to implement very-large-scale integration chips. Silicon germanium (SiGe) is an alloy with any molar ratio of silicon and germanium, which is commonly used as a semiconductor material in integrated circuits for HBTs or as a strain-inducing layer for CMOS transistors. This relatively new technology offers opportunities in mixed-signal and analog integrated circuit design and manufacturing. SiGe is also used as a thermoelectric material for high temperature applications process. 718 Chapter 5 Fully depleted/partially dep