The Figure of Merit of a Semiconductor Power Electronics Switch

The figure of merit (FOM) of a semiconductor device represents an important quality as it pertains to its performance limits and is often used to drive the technology development in a specific direction. Comparing the performances of switching power MOSFETs using their FOMs has become ubiquitous practice in power semiconductor and power electronics industries. In this paper, a critical review of the proposed power MOSFET FOMs is presented, and key limitations are discussed. It is shown that the quality factor Q(F2) = (lambda E-c/R-ON,R-sp) along with Q(G) and T-jmax may be used to guide the development of future generations of power semiconductor device technologies for power electronics switching applications, where lambda and E-c are the thermal conductivity and critical electric field strength for the avalanche breakdown of the semiconductor material, respectively, R-ON,R-sp is the specific on-state electrical resistance, Q(G) is the gate charge, and T-jmax is the maximum junction temperature of the semiconductor power device, respectively.