Elemental and compound semiconductors, including widebandgap semiconductors, are critically examined for high-power electronic applications in terms of on-state resistance, power loss caused by junction leakage, heat conduction, radiation hardness, high-frequency performance, and high-temperature operation. Based on a new analysis applicable to a wide range of semiconducting materials and by using the available measured physical parameters, it is shown that widebandgap semiconductors such as SIC and diamond could offer significant advantages compared to either silicon or group 111-V compound semiconductors for these applications. The new analysis uses peak electric field strength at avalanche breakdown as a critical material parameter for evaluating the quality of a semiconducting material for highpower electronics. Theoretical calculations show improvement by orders of magnitude in the on-resistance, twentyfold improvement in the maximum frequency of operation, and potential for successful operation at temperatures beyond 600°C for diamond high-power devices. New figures of merit for power-handling capability that emphasize electrical and thermal conductivities of the material are derived and are applied to various semiconducting materials. It is shown that improvement in power-handling capabilities of semiconductor devices by three orders of magnitude is feasible by replacing silicon with silicon carbide; improvement in power-handling capability by six orders of magnitude is projected for diamond-based devices.

Applicability of GaN in unipolar and bipolar devices for high-power electronic applications is evaluated with respect to similar devices based on other materials. Specific resistance is used as a measure of unipolar performance. In order to evaluate bipolar performance, 700 and 6000 V p-i-n diodes based on Si, 6H-SiC, and GaN are compared with respect to forward conduction and reverse recovery performance at room temperature and high-temperature conditions. It is shown that GaN is advantageous not only for high voltage unipolar applications, but also for bipolar applications. An empirical closed-form expression is presented to predict the avalanche breakdown voltage of wide band-gap semiconductors. Formulation of the expression is based on an approximation of the impact ionization coefficient in terms of seventh power of the electric field.

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The current state-of-the-art of wide bandgap (WBG) semiconductor material technology is reviewed for the manufacturing of high-performance and reliable power electronics switching devices. In particular, silicon carbide (SiC) and gallium nitride (GaN) material and device technologies are evaluated when compared to conventional silicon power switching devices. For commercial applications above 400 volts, SiC stands out as a viable near-term commercial opportunity especially for single-chip current ratings in excess of 20 amps. For voltage ratings below 900 volts and smaller currents (below 20 amps), lateral GaN power transistors that utilize two-dimensional electron gas (2DEG) are promising candidates. At the time of this writing, field-reliability of WBG power devices is yet to be demonstrated in power converter applications. The exact role of high-density of material defects in both SiC and GaN semiconductors, primarily in the drift-region of the device, is not known from manufacturing and reliability considerations. This fundamental understanding is critical in order for WBG power devices to rapidly penetrate the vast commercial and strategic markets.