State of the SiC MOSFET

12th December 2017

Lanna Deamer

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It is highly unlikely that anyone reading this article is unfamiliar with the Insulated Gate Bipolar Transistor (IGBT). This disruptive power transistor, first commercialised in the early 1980s, has had an enormous positive impact on the power electronics industry, enabling innovative converter design, improved system efficiencies, and worldwide energy savings. Indeed, some estimates suggest the IGBT has helped forestall 75 trillion pounds of CO₂ emissions over the past 25 years.

Much as the IGBT was revolutionary in the 1980s, today the wide band gap semiconductor Silicon Carbide (SiC) shows increasing promise for revolutionising the power electronics world once again. The IGBT gave us a transistor simultaneously capable of blocking high voltages with low on-state (i.e. conduction) losses and well-controlled switching.

The device is limited, however, in how fast it may be switched, which leads to high switching losses, large and expensive thermal management, and a ceiling on power conversion system efficiency. The advent of SiC transistors all but eliminates an IGBT’s switching losses for similar on-state losses (lower, actually, at light load) and voltage-blocking capability, enabling unprecedented efficiency in addition to reducing the overall weight and size of the system.

Like most disruptive technologies, however, the evolution of commercial SiC power devices has traveled a tumultuous road. This article is intended to put the evolution of the SiC MOSFET in context, and - along with an abridged history of the device’s advancements - present its technology merits today and its commercial prospects for the future.