Kim Je-Hyuk, Jang Jun Tae, Bae Jong-Ho, Choi Sung-Jin, Kim Dong Myong, Kim Changwook, Kim Yoon, Kim Dae Hwan
The School of Electrical Engineering, Kookmin University, Seoul 02707, Korea.
Circadian ICT Research Center, Kookmin University, Seoul 02707, Korea.
Micromachines (Basel). 2021 Mar 19;12(3):327. doi: 10.3390/mi12030327.
In this study, we analyzed the threshold voltage shift characteristics of bottom-gate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) under a wide range of positive stress voltages. We investigated four mechanisms: electron trapping at the gate insulator layer by a vertical electric field, electron trapping at the drain-side GI layer by hot-carrier injection, hole trapping at the source-side etch-stop layer by impact ionization, and donor-like state creation in the drain-side IGZO layer by a lateral electric field. To accurately analyze each mechanism, the local threshold voltages of the source and drain sides were measured by forward and reverse read-out. By using contour maps of the threshold voltage shift, we investigated which mechanism was dominant in various gate and drain stress voltage pairs. In addition, we investigated the effect of the oxygen content of the IGZO layer on the positive stress-induced threshold voltage shift. For oxygen-rich devices and oxygen-poor devices, the threshold voltage shift as well as the change in the density of states were analyzed.
在本研究中，我们分析了底栅非晶铟镓锌氧化物（IGZO）薄膜晶体管（TFT）在宽范围正应力电压下的阈值电压漂移特性。我们研究了四种机制：垂直电场在栅极绝缘层处的电子俘获、热载流子注入在漏极侧栅极绝缘层处的电子俘获、碰撞电离在源极侧蚀刻停止层处的空穴俘获以及横向电场在漏极侧IGZO层中产生类施主态。为了准确分析每种机制，通过正向和反向读出测量源极和漏极侧的局部阈值电压。通过使用阈值电压漂移的等高线图，我们研究了在各种栅极和漏极应力电压对中哪种机制占主导。此外，我们研究了IGZO层的氧含量对正应力诱导的阈值电压漂移的影响。对于富氧器件和贫氧器件，分析了阈值电压漂移以及态密度的变化。
