This paper presents an investigation of the abnormal hump phenomenon in amorphous indium gallium zinc oxide thin-film transistors under positive gate bias and temperature stress (PBTS). During PBTS, the current-voltage curve shows a severe hump and an abnormal double hump. Additional stress tests were conducted under long-term and low-temperature PBTS and current stress (CS), then the capacitance-voltage (C-V) curves after PBTS and CS were compared to identify the causes of the double-hump phenomenon. Threshold voltages V_T were extracted at two levels of normalized drain current I_DS: high V_{T_H} at I_DS = 10^-8 A and low V_{T_L} at I_DS = 10^-12 A. After 10,000 s, high-temperature PBTS shifted V_{T_H} by + 3.48 V and V_{T_L} by –3.20 V; low-temperature PBTS shifted V_{T_H} by + 1.46 V and V_{T_L} by –0.56 V; and CS shifted V_{T_H} by + 5.02 V and V_{T_L} by –0.98 V. Saturation measurement indicated that degradation of the source region has the strongest influence on degradation of I_DS-V_GS during CS; these results indicate trapping of charged species. In addition, both high-temperature PBTS and CS affected the C-V results; these changes indicate creation of defect states. Therefore, we hypothesize that the severe hump occurred because of a combination of trapping of charged species and creation of defect states. The double hump occurred only during PBTS. Thus, we hypothesize that the double hump was caused by trapping of ionized oxygen vacancies in the back channel. In a 2D TCAD simulation, the proposed hypothesis suggests that the migration of defect states and charged species affect the hump phenomenon. By changing distribution of shallow donor-like states in the channel and by changing the number of trapped electrons, we obtained simulated curves that were well fitted to our experimental results.

本文研究了在正栅极偏置和温度应力（PBTS）下非晶铟镓锌氧化物薄膜晶体管的异常驼峰现象。在PBTS期间，电流-电压曲线显示出严重的驼峰和异常的双驼峰。在长期低温PBTS和电流应力（CS）下进行了额外的应力测试，然后比较了PBTS和CS之后的电容-电压（CV）曲线，以确定双峰现象的原因。在归一化的漏极电流I _DS的两个电平处提取阈值电压V _T：I _DS  = 10 ^-8 A时的高V _{T_H}和低V_{T_L}在我_DS  = 10 ^-12 A.后万个S，高温PBTS偏移V _{T_H}由+ 3.48 V和V _{T_L}由-3.20 V; 低温PBTS将V _{T_H}偏移+ 1.46 V，将V _{T_L偏移}–0.56 V；和CS移位V _{T_H}由+ 5.02 V和V _{T_L}由-0.98 V.饱和度测量中指示的源极区的劣化对降解最强影响我_DS - V _GSCS期间 这些结果表明捕获带电物种。此外，高温PBTS和CS都会影响CV结果; 这些变化表明缺陷状态的产生。因此，我们假设发生严重的驼峰是由于带电种类的捕获和缺陷状态的产生的结合。双重驼峰仅在PBTS期间发生。因此，我们假设双重驼峰是由于在后通道中捕获了电离的氧空位引起的。在二维TCAD仿真中，提出的假设表明缺陷状态和带电物质的迁移会影响驼峰现象。通过改变通道中浅施主态的分布并改变俘获电子的数量，我们获得了与实验结果完全吻合的模拟曲线。