Wide and narrow bandgap semiconductors for power electronics: A new valuation

An advantage for some wide bandgap materials that is often overlooked is that the thermal coefficient of expansion (CTE) is better matched to the ceramics in use for electronic-packaging technology. The optimal choice for unipolar devices is GaN and the associated material system of GaN/AlGaN. The future optimal choice for bipolar devices at all power levels is C (diamond). New expressions, ɛc=1.73×105 (EG)2.5 for direct-gap and ɛc=2.38×105 (EG)2 for indirect-gap semiconductors, relating the critical-electric field for breakdown in abrupt junctions to the material bandgap energy, and associated new expressions for specific on-resistance in power semiconductor devices is shown to further support the use of wide bandgap materials. Some low-voltage, power-electronics applications are shown to benefit by the use of Ge, C, and GaSb.