Optimization and design of diamond High Voltage power devices
Résumé
Diamond, thanks to its outstanding physical properties, is the
ultimate semiconductor to go beyond the classical design trade off in power
devices. The two switches (Schottky Barrier Diode and Field Effect
Transistor (FET)) which will allow fabricating a full diamond commutation cell
for power converters are under investigation. Nevertheless, to take benefit
of diamond properties in such components a particular attention has to been
paid to the design of the structure based on the most recent experimental
characterization of diamond physical parameters. In this work, we focused
on the optimization of the Ron.S(BV) figure of merit while sizing the drift layer
of unipolar high voltage diamond power devices. Based on the ionization
integral calculation with diamond adapted impact ionization coefficients in a
one dimensional semi-analytical approach of the breakdown voltage, we
performed an accurate analysis of the reciprocal punch through factor as
function of the breakdown voltage. In the case of diamond FETs, we also
evaluated the minimum channel dose (doping level times thickness) avoiding
the pinch of the channel and so ensuring a good operating regime for
diamond p-FET. These results will allow proposing preliminary design rules
to fabricate working unipolar diamond power devices. However we will show
that thickness and doping required for such structures are quite challenging
for crystal growth in the context of high voltage power devices.