Influence of Carbon on pBTI Degradation in GaN-on-Si E-Mode MOSc-HEMT

Abstract

In this article, threshold-voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instabilities under positive gate voltage stress V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GStress</sub> in GaN-on-Si devices are thoroughly investigated. Measurement-stress-measurement pBTI technique using ultrafast V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> ramp was applied in this study. PBTI transients performed at different V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GStress</sub> and several temperatures highlight the influence of two trap populations, one being related to 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 defects and the other one to C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> acceptors in GaN lattice. Both trap populations are located close to the 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> /GaN interface and lead to V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instabilities via two different underlying mechanisms simulated by TCAD. PBTI transients obtained under several dc and ac stress conditions have also been modeled using capture emission time (CET) maps and allowed the identification of the two trap populations. Analysis of the temperature-dependent CET maps gives an activation energy of 0.8-0.9 eV related to C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> traps and an energy range between 0.7 and 1.5 eV ascribed to 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> defects above the GaN conduction band energy. This study provides a better understanding of the underlying physical mechanisms, leading to BTI degradation in GaN-HEMT technologies.