Modelling the threshold voltage of normally off p channel transistors in GaN

What is it about?

Getting a sufficiently high negative threshold voltage in a p-channel GaN device is a considerable challenge. Using Gauss Law, we have derived simple expressions based on material parameters that can intuitively predict the threshold voltage via back-of-hand calculations. Two types of heterostructures have been evaluated in terms of the device current and on/off ratio as a function of threshold voltage using the analytic expressions.

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Why is it important?

p-type devices are needed to enable CMOS circuits in GaN. If such technology were available, then CMOS gate drivers could be integrated with power devices on the same chip. CMOS can prevent shoot-through failure which is necessary for many applications. GaN can enable higher efficiency power conversion and is a much greener technology than silicon.

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