Because of its wide bandgap, high thermal stability, and resistance to corrosive environments, SiC is an enabling technology for many applications that cannot be served by conventional semiconductors. Among these applications are high-power microwave devices for commercial and military systems; high-temperature electronics for automotive, aerospace, and well-logging; rugged MEMSs (micro-electro-mechanical sensor) devices for hostile environments; gas and chemical sensors for internal combustion engines, furnaces, and boilers; and solar-blind UV photodetectors. We will discuss each of these applications in this chapter.
12.1 Microwave Devices
SiC has a higher breakdown field, higher saturation drift velocity, and higher thermal conductivity than silicon or GaAs, making it an ideal material for microwave power generation at frequencies in the L and S bands (1–2 and 2–4 GHz). SiC devices are extremely robust, and both microwave MESFETs (metal-semiconductor field-effect transistors) and static induction transistors (SITs) have entered commercial production.
12.1.1 Metal-Semiconductor Field-Effect Transistors (MESFETs)
SiC microwave MESFETs were developed between 1995 and 2002 as replacements for GaAs microwave field-effect transistors (FETs) . Figure 12.1 shows the cross-section of a SiC MESFET, along with typical dopings and dimensions. The gate metal forms a Schottky contact with the n-type channel layer, and ...