Breakdown voltage enhancement for GaN high electron mobility transistors

This paper presents a high voltage AlGaN/GaN HEMTs with remarkable breakdown voltage enhancement by introducing a magnesium doping layer under the 2-DEG channel. The surface electric field is distributed more evenly when compare to a conventional device structure with the same dimensions. This is primarily due to the presence of a charge balanced magnesium doping layer acting as a floating field plate. By optimizing the layer´s length, L and the doping concentration, a breakdown voltage of 900V with specific on resistance of 4mΩ·cm² was obtained with L = 1.5μm, a peak concentration of 8×10¹⁷cm^-3 and a drift region length of 10μm. Comparing with previously published breakdown optimization techniques, this work achieved a 100% improvement in specific on-resistance without any area overhead penalty.