Investigation of nBTI degradation on GaN-on-Si E-mode MOSc-HEMT

Abstract

In this paper, we investigate the influence of negative gate stress on threshold voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instabilities in GaN-on-Si devices. This study has been carried out by using ultra-fast Measurement-Stress-Measurement (MSM) procedure on GaN-on-Si E-mode MOSc-HEMTs (Enhancement-mode MOS-channel HEMTs) for different gate lengths L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> . NBTI transients at different temperatures and complementary ToF-SIMS analysis reveal the influence of two trap populations involved on V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instabilities, both of them are related to the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> acceptor traps. The first one is close to the interface between GaN and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gate oxide due to N-vacancies induced by the dry etching process, the second one is likely to be related to GaN:C layer. NBTI transients also exhibit a dependence with L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> , which is consistent with the E-field distribution of the gate region obtained by TCAD simulations at different gate stress voltages, and confirm the proximity of a C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> trap population to the gate oxide.