Reduction of peak electric field strength in GaN-HEMT with carbon doping layer

We propose a reduction in the peak electric field strength at the drain side of the gate electrode in a high-electron mobility transistor using a carbon-doped GaN layer. Simulation results indicated that the peak electric field strength decreased with decrease in the spacing between the 2-dimensional electron gas (2DEG) channel and the carbon doped GaN layer due to the acceptor-like states of carbon. Experimental results supported the simulation results by the higher breakdown voltages obtained with smaller spacing layers. Current collapse phenomena were relatively suppressed with a 0.5 mu m thick spacing layer compared to 2 or 3 mu m thick spacing layers, due to reduction of the electric field strength. From these results, we could conclude that the carbon doped GaN layer enables the combination of high breakdown voltage and low current collapse by improved design of the spacing between the channel and the carbon containing layer in a GaN-based device. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim