Diamond devices in power converters: needs, constraints, and impact
Résumé
Semiconductor devices for power electronics are quite distinctive from those used in low power or high frequency applications. They operate in switched mode operation, switching from ON state to OFF state and vice-versa. First, the power devices should be designed to withstand high voltages in OFF state, higher than
30 V and up to several tens of kilovolts. Consequently, a drift layer is required,which must be lightly doped and deep to accommodate the depletion region formed
across a reverse biased junction. For higher voltage devices (above 100 V), this region is responsible for most of the total series resistance. Second, the power devices need to transpor t high currents in the ON state (from hundreds of mA to thousands of amps) with a minimal voltage drop between the main terminal to
reduce ON state losses. Switching between the ON and the OFF states results in additional losses which are proportional to the operating frequency. Therefore, opti-
mizing the losses dissipated by each power device for a fixed device area has been a key goal since the early days of power electronics.