Recently, new technologies represented by VR (Virtual Reality) and AR (Augmented Reality) are getting much attention as the killer application for the next-generation display. Many devices such as Oculus lift,Gear VR and Hololens have already shown us the possibilities of the realization of those new technologies. However, there still remain several critical issues, and one of them is the resolution of display. For example, the latest high-end smartphone displays on the market usually offers 500~600 ppi (pixels per inch) of pixel density, and it is not enough to give the sense of reality to the VR or AR users. To solve this problem, higher resolution and pixel density of several thousands ppi are expected to be desired for the next-generation display. In that point, oxide semiconductor based vertical structure thin-film transistor (VTFT) can be a good candidate for the backplane of future display. Due to its vertical channel structure, it gives smaller footprint than the conventional BCE structure TFT. Therefore, it is able to reduce the size of pixels and offer more pixels within a display panel. Moreover, it is possible to downsize the channel length under 1um by using the existing photolithography equipments. This can give us enhanced current drivability, and higher on-current level.
 J. Kim et al. "Channel-Shortening Effect Suppression of a High-Mobility Self-Aligned Oxide TFT using Trench Structure", IEEE Electron Device Letters, 2021