Comparison of Hetero and Mono FET and BT Structures Hrvoje Ocevcic, Tomislav Svedek

The properties of hetero and mono FET and BT devices are reviewed and discussed in the context of their suitability for high frequency and noise. GaAs based devices have a defined place in commercial and many more applications. The heterojunction bipolar transistor (HBT) basically is a modified bipolar transistor. The emitter and base layers are formed with different bandgap material. The emitter having the wider band gap, thus the emitter delivers a barrier against the hole injection into the base. HBT technology has become a major player in wireless communication, power amplifier, mixer, and frequency synthesizer applications. HBTs extend the advantages of silicon bipolar transistors to significantly higher frequencies. The HEMT delivers the lowest noise figure with a high gain performance. This high gain in some cases is a disadvantage for problem free volume applications in low frequency range