Small <i>V</i> <sub>th</sub> Shift and Low Dynamic <i>R</i> <sub>on</sub> in GaN MOSHEMT With ZrO<sub>2</sub> Gate Dielectric
Yu Zhang, Yitian Gu, Jiaxiang Chen, Yitai Zhu, Baile Chen, Huaxing Jiang, Kei May Lau, Xinbo Zou
Abstract
The OFF-state stress-induced threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> ) instability and dynamic ON-resistance ( <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> ) of GaN metal-oxide-semiconductor high-electron mobility transistor (MOSHEMT) with ZrO2 gate dielectric are thoroughly investigated. Upon negative gate bias stressing, a small threshold voltage shift of −0.31 V is observed and the deviation is attributed to the emission of electrons at the ZrO2/AlGaN interface. An emission activation energy of 0.28 eV and a capture activation energy of 0.30 eV are extracted by threshold voltage transient spectroscopy performed at various temperatures. When the device is exposed to OFF-state drain–source bias stressing, the drain current is found to decrease despite negative shift of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> . A low 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> of 2.05 is obtained by time-resolved measurements, given a 50-V drain voltage stressing for a duration of 100 s. The decrease in forward conductance is related to the capture of electrons in the access region, with a capture activation energy of 0.18 eV revealed by temperature-dependent drain current transient (DCT) analysis. The results indicate that high-quality ZrO2 represents an attractive high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> gate dielectric option for GaN MOSHEMTs in power switching electronics.