Partial Recovery of Dynamic <i>R</i> <sub>ON</sub> Versus OFF-State Stress Voltage in p-GaN Gate AlGaN/GaN Power HEMTs
Marcello Cioni, Nicolò Zagni, Ferdinando Iucolano, Maurizio Moschetti, G. Verzellesi, Alessandro Chini
Abstract
Dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\mathrm{\scriptscriptstyle {ON}}}$ </tex-math></inline-formula> dispersion due to buffer traps is a well-known issue of GaN power high electron mobility transistors (HEMTs), critically impacting their performance and stability. Several works show that the dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\mathrm{\scriptscriptstyle {ON}}}$ </tex-math></inline-formula> reaches a maximum for some OFF-state drain–source voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text{DS},{\mathrm{\scriptscriptstyle OFF}}}$ </tex-math></inline-formula> ) value typically in the range of several hundred volts and then partially recovers to smaller values. In this work, we propose a quantitative explanation for this behavior, attributing it to the charging/discharging dynamics of carbon (C)-related buffer traps. We characterize the dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\mathrm{\scriptscriptstyle {ON}}}$ </tex-math></inline-formula> in packaged p-GaN gate AlGaN/GaN HEMTs with a custom measurement setup. We find that in these devices, the relative <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\mathrm{\scriptscriptstyle {ON}}}$ </tex-math></inline-formula> increase reaches a maximum of 60% for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {DS}, {\mathrm{\scriptscriptstyle {OFF}}}} \approx 100$ </tex-math></inline-formula> –200 V, partially recovering to about 30% as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {DS}, {\mathrm{\scriptscriptstyle {OFF}}}}$ </tex-math></inline-formula> is raised to 500 V. We ascribe this behavior to the partial neutralization of C-related acceptor traps in the buffer due to trapping of holes produced by a high-field generation mechanism. This explanation is supported by calibrated 2-D numerical simulations, that successfully reproduce the experimentally observed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\mathrm{\scriptscriptstyle {ON}}}$ </tex-math></inline-formula> reduction only when including a hole generation mechanism.