Silicon carbide (SiC) semiconductor devices for high power applications are now commercially available as discrete devices. Recently Schottky diodes are offered by both USA and Europe based companies. Active switching devices such as bipolar junction transistors (BJTs), field effect transistors (JFETs and MOSFETs) are now available on the commercial market. The interest is rapidly growing for these devices in high power and high temperature applications. The main advantages of wide bandgap semiconductors are their very high critical electric field capability. From a power device perspective the high critical field strength can be used to design switching devices with much lower losses than conventional silicon based devices both for on-state losses and reduced switching losses. This paper reviews the current state of the art in active switching device performance for both SiC and GaN. SiC material quality and epitaxy processes have greatly improved and degradation free 100 mm wafers are readily available. The SiC wafer roadmap looks very favorable as volume production takes off. For GaN materials the main application area is geared towards the lower power rating level up to 1 kV on mostly lateral FET designs. Power module demonstrations are beginning to appear in scientific reports and real applications. A short review is therefore given. Other advantages of SiC is the possibility of high temperature operation (>; 300°C) and in radiation hard environments, which could offer considerable system advantages.

A monolithic bipolar operational amplifier (opamp) fabricated in 4H-SiC technology is presented. The opamp has been used in an inverting negative feedback amplifier configuration. Wide temperature operation of the amplifier is demonstrated from 25°C to 500°C. The measured closed loop gain is around 40 dB for all temperatures whereas the 3 dB bandwidth increases from 270 kHz at 25°C to 410 kHz at 500°C. The opamp achieves 1.46 V/μs slew rate and 0.25% total harmonic distortion. This is the first report on high temperature operation of a fully integrated SiC bipolar opamp which demonstrates the feasibility of this technology for high temperature analog integrated circuits.

Epitaxial Ti3SiC2 (0001) thin film contacts were grown on doped 4H-SiC (0001) using magnetron sputtering in an ultra high vacuum system. The specific contact resistance was investigated using linear transmission line measurements. Rapid thermal annealing at 950 °C for 1 min of as-deposited films yielded ohmic contacts to n-type SiC with contact resistances in the order of 10−4 Ω cm2. Transmission electron microscopy shows that the interface between Ti3SiC2 and n-type SiC is atomically sharp with evidence of interfacial ordering after annealing.

Implantation-free mesa-etched 4H-SiC PiN diodes with a near-ideal breakdown voltage of 4.3 kV (about 80% of the theoretical value) were fabricated, measured, and analyzed by device simulation and optical imaging measurements at breakdown. The key step in achieving a high breakdown voltage is a controlled etching into the epitaxially grown p-doped anode layer to reach an optimum dopant dose of ~ 1.2 times 10¹³ cm^-2 in the junction termination extension (JTE). Electroluminescence revealed a localized avalanche breakdown that is in good agreement with device simulation. A comparison of diodes with single- and double-zone etched JTEs shows a higher breakdown voltage and a less sensitivity to varying processing conditions for diodes with a two-zone JTE.

Undoped single crystalline aluminum nitride films were grown on 4H and 6H SiC substrates using metal–organic chemical-vapor deposition at 1200 °C. From in situ reflection high-energy electron diffraction, x-ray diffraction rocking curves, and cathodoluminescence spectra, the crystallinity of the films was confirmed. Atomic force microscopy showed that some films were substantially dominated by island growth, rather than step flow growth. Aluminum was evaporated to form metal–insulator–semiconductor (MIS) capacitors for high-frequency capacitance voltage measurements carried out at room temperature. Low leakage made it possible to measure the structures and characterize accumulation, depletion, deep depletion, and, in some cases, inversion. From independent optical thickness measurements, the relative dielectric constant of aluminum nitride was confirmed at 8.4. The flatband voltage of the AlN MIS capacitors on $p$ -type SiC was close to the theoretical value expected. The films were stressed up to 60 V (3 MV/cm) without breakdown, but excessive leakage currents $\text{(>0.1\hspace{0.17em}}{\mathrm{A/cm}}^{\mathrm{2}}\mathrm{),}$ probably dominated by grain-boundary conduction, shifted the flatband voltage of the capacitors. These results indicate the possibility of replacing silicon dioxide with aluminum nitride in SiC field effect transistors using insulated gates.