ABSTRACT
This chapter provides information on important materials properties of semiconductors used for microwave and Radio Frequency (RF) applications. The amount of free charge in the semiconductor and the transport characteristics of the charge within the crystalline lattice determine the conductivity. Material characteristics vary in semiconductors and only certain materials are suitable for use in the fabrication of microwave and RF devices. Electron transport properties determine, to a large extent, the frequency at which the various semiconductors are used. Bulk semiconductors, for microwave and RF applications, include germanium (Ge), silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), and indium phosphide (InP). Si and Ge have the same crystal structure as diamond. In comparison with Si and GaAs, SiC has greater than 2.5x larger bandgap, 3x greater thermal conductivity, and a factor of 10 larger breakdown electric field. A new class of high performance materials, based on GaAs and InP, has been developed using advanced epitaxial processes such as molecule beam epitaxy.
