Optimization of Vertical GaN Drift Region Layers for Avalanche and Punch-Through Pn-Diodes
Enrico Brusaterra, E. Bahat Treidel, Frank Brunner, Mihaela Wolf, A. Thies, Joachim Würfl, Oliver Hilt
Abstract
We optimized gallium nitride drift layers for high voltage and low resistance vertical electronic devices by tuning the doping concentration for a given thickness of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . The optimization procedure is based on an empirical mobility model in order to maximize the corresponding device’s power figure-of-merit with respect to the drift layers parameters. We demonstrate quasi-vertical gallium-nitride based avalanche and punch-through pn-diodes grown on sapphire substrates and we compare the results to the theoretical breakdown voltage values as a function of the drift region doping concentration and thickness. We report on a pn-diode with 545 V avalanche breakdown voltage and a specific resistance of 0.34 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> cm2 resulting in a power figure-of-merit of 874 MW / cm2 and a punch-through pn-diode with 920 V breakdown voltage, specific resistance of 0.57 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> cm2 resulting in a power figure-of-merit of 1.48 GW / cm2.