Hydrogen-Induced Reversible Changes In Drain Current In Sc2o3/Algan/Gan High Electron Mobility Transistors

Pt contacted AlGaN/GaN high electron mobility transistors with Sc2O3 gate dielectrics show reversible changes in drain-source current upon exposure to H-2-containing ambients, even at room temperature. The changes in current (as high as 3 mA for relatively low gate voltage and drain-source voltage) are approximately an order of magnitude larger than for Pt/GaN Schottky diodes and a factor of 5 larger than Sc2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) diodes exposed under the same conditions. This shows the advantage of using a transistor structure in which the gain produces larger current changes upon exposure to hydrogen-containing ambients. The increase in current is the result of a decrease in effective barrier height of the MOS gate of 30-50 mV at 25degreesC for 10% H-2/90% N-2 ambients relative to pure N-2 and is due to catalytic dissociation of the H-2 on the Pt contact, followed by diffusion to the Sc2O3/AlGaN interface. (C) 2004 American Institute of Physics.