Liu Jie, Guo Jianlei, Yang Wenlong, Wang Cuiru, Yuan Bin, Liu Jia, Wu Zhiheng, Zhang Qing, Liu Dapu, Chen Huixin, Yu Yinyin, Liu Suilin, Shao Guosheng, Yao Zhiqiang
State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
OLED Product Development Department, Tianma Microelectronics Co., Ltd., No. 9 Zuoling Boulevard, Hongshan District, Wuhan 430074, China.
ACS Appl Mater Interfaces. 2020 Sep 30;12(39):43950-43957. doi: 10.1021/acsami.0c13873. Epub 2020 Sep 18.
InGaZnO (IGZO) is currently the most prominent oxide semiconductor complement to low-temperature polysilicon for thin-film transistor (TFT) applications in flat panel displays. However, the compromised transport performance and bias stress instability are critical issues inhibiting its application in ultrahigh-resolution optoelectronic displays. Here, we report the fabrication of graded channel junctionless IGZO:O|N TFTs with both high transporting properties and good bias stress stability by systematic manipulation of oxygen vacancy (V) defects through sequential O antidoping and O/N codoping of the continuous IGZO framework. The transporting properties and bias stress stability of the graded channel IGZO:O|N TFTs, which exhibited high field-effect mobilities close to 100 cm V s, negligible performance degradations, and trivial threshold voltage shifts against gate bias stress and photobias stress, are simultaneously improved compared to those of the controlled single-channel uniformly doped IGZO:O TFTs, IGZO:N TFTs, and double-channel barrier-confined IGZO:O/IGZO:N TFTs. The synergistic improvements are attributed to the sequential mobility and stability enhancement effects of O antidoping and O/N codoping where triple saturation currents are induced by O antidoping of the front-channel regime while the trapped electrons and photoexcited holes in the back-channel bulk and surface regions are suppressed by O/N codoping. More importantly, fast accumulation and barrier-free full depletion are rationally realized by eliminating the junction interface within the graded channel layer. Our observation identifies that graded channel doping could be a powerful way to synergistically boost up the transport performance and bias stress stability of oxide TFTs for new-generation ultrahigh-definition display applications.
铟镓锌氧化物（IGZO）目前是平板显示器中薄膜晶体管（TFT）应用中最突出的氧化物半导体，可作为低温多晶硅的补充。然而，其传输性能的折衷和偏置应力不稳定性是阻碍其在超高分辨率光电显示器中应用的关键问题。在此，我们报告了通过对连续IGZO框架进行顺序氧反掺杂和氧/氮共掺杂，系统地操纵氧空位（V）缺陷，制备出具有高传输性能和良好偏置应力稳定性的渐变沟道无结IGZO:O|N TFT。与受控的单沟道均匀掺杂IGZO:O TFT、IGZO:N TFT和双沟道势垒限制IGZO:O/IGZO:N TFT相比，渐变沟道IGZO:O|N TFT的传输性能和偏置应力稳定性同时得到改善，其场效应迁移率接近100 cm² V⁻¹ s⁻¹，性能退化可忽略不计，且相对于栅极偏置应力和光偏置应力的阈值电压偏移很小。这些协同改进归因于氧反掺杂和氧/氮共掺杂的顺序迁移率和稳定性增强效应，其中前沟道区域的氧反掺杂诱导了三重饱和电流，而后沟道体区和表面区域中的俘获电子和光激发空穴则被氧/氮共掺杂抑制。更重要的是，通过消除渐变沟道层内的结界面，合理地实现了快速积累和无势垒的完全耗尽。我们的观察表明，渐变沟道掺杂可能是一种有效提高氧化物TFT传输性能和偏置应力稳定性的有力方法，可用于新一代超高清晰度显示应用。
