Improved Interface Properties and Dielectric Breakdown in Recessed AlGaN/GaN MOS-HEMTs Using HfSiO<inline-formula> <tex-math notation="LaTeX">$_{{x}}$ </tex-math> </inline-formula> as Gate Dielectric

Abstract

In this letter, we report optimized transport properties in gate recessed enhancement-mode GaN MOS-HEMTs by incorporating silicon into atomic layer deposited gate dielectric HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Compared with commonly used HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gate dielectric, the interface trap density can be reduced by nearly an order of magnitude and the fixed oxide traps inside are reduced to almost half using the high-quality passivation of HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> . The MOS-HEMTs based on HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> exhibit a threshold voltage of 1.5 V, excellent subthreshold swing of 65 mV/dec, and a high on-off ratio of 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> . The incorporation of silicon in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can also increase the dielectric breakdown property with maximum gate electric field of 2.85 MV/cm for a 10-year time-dependent gate dielectric breakdown lifetime, which is 36% higher than pure HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The maximum breakdown voltage of HfSiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> MOS-HEMT is 742 V, which is 30% higher than HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> MOS-HEMT.