Experimental observation and physics of “negative” capacitance and steeper than 40mV/decade subthreshold swing in Al<inf>0.83</inf>In<inf>0.17</inf>N/AlN/GaN MOS-HEMT on SiC substrate

Abstract

GaN is a promising material for LED lighting [1], high voltage power electronics [2] and high power RF applications [3]. GaN HEMT and MOS-HEMT with AlGaN [4] or AlInN [5] polarization layer have been widely studied. In this work we investigate the effects of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.83</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.17</sub> N polarization layer thickness scaling on the device characteristics of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.83</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.17</sub> N/AlN/GaN MOS-HEMTs on SiC substrates. We have experimentally observed “negative” capacitance and subthreshold swing (SS) steeper than 40 mV/dec in GaN MOS-HEMTs with thin Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.83</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.17</sub> N polarization layer, where composition modulation of Al% and In% is observed.