Gate Bias Effects on Hydrogen-Terminated Polycrystalline Diamond FETs
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2023-12-06 |
| Journal | IEEE Transactions on Electron Devices |
| Authors | Hongyue Wang, Yuebo Liu, Lei Ge, Mingsheng Xu, Yijun Shi |
| Institutions | Peking University, Ministry of Industry and Information Technology |
| Citations | 1 |
Abstract
Section titled “Abstract”In this article, gate bias ( <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>${V}{\text {GS},\text {stress}}{)}$ </tex-math></inline-formula> effects on the hydrogen (H)-terminated polycrystalline diamond field effect transistors (FETs) are investigated. A 7- to 8-nm AlOx interface layer is found between the Al metal and polycrystalline diamond by electrical and microstructure characterization. The 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> and 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”>${R}{\text {on}}{)}$ </tex-math></inline-formula> exhibit different changing trends under varying <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>${V}{\text {GS},\text {stress}}$ </tex-math></inline-formula> . Specifically, a bidirectional 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> is observed during gate bias stress. To explain the distinct behavior 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> shift and <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>${R}_{\text {ON}}$ </tex-math></inline-formula> change occurring under gate bias, holes trapping by defects, H-motion, and surface leakage electron trapping models are proposed. Under negative gate bias, holes in 2-D hole gas channel are captured by the interface states and/or defects in the AlOx layer, resulting in a 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> . Simultaneously, H-motion in the AlOx layer under gate bias leads to the generation of negative charges. Additionally, electrons in the surface leakage path are trapped by defects on the diamond surface in the access region, leading to decreased access region resistance. For a harsh gate bias, a high density of new defects is generated, and a defect density changes from <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>$4.9\times 10^{{21}}$ </tex-math></inline-formula> ev−1cm−3 for the fresh device to <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>$5.1\times 10^{{23}}$ </tex-math></inline-formula> ev−1cm−3 for the device after gate bias ( <inline-formula xmlns:mml=“http://www.w3.org/1998/Math/MathML” xmlns:xlink=“http://www.w3.org/1999/xlink”> <tex-math notation=“LaTeX”>${V}{\text {GS},\text {stress}}$ </tex-math></inline-formula> = −4 V) which is characterized by using the low-frequency noise measurements. These findings highlight the importance of surface passivation and high-quality gate dielectric in suppressing charging effects and new defect generation in H-terminated polycrystalline diamond FETs, ultimately contributing to device stability.