Letter: Mechanisms for on/off currents in dual‐gate a‐Si:H thin‐film transistors using indium‐tin‐oxide top‐gate electrodes

Abstract

Two types of dual-gate a-Si:H TFTs were made with transparent indium-tin-oxide (ITO) top-gate electrodes of different lengths to investigate the static characteristics of these devices. By changing the length of the ITO top gate, we found that the variations in the on-currents of these dualgate TFTs with dual-gate driving are due to the high resistance of the parasitic intrinsic a-Si:H regions between the back electron channel and the source/drain contact. In the off-state of the dual-gate-driven TFTs, the Poole-Frenkel effect is also enhanced due to back-channel hole accumulation in the vicinity of the source/drain contact. Furthermore, we observed for the first time that under illumination the dual-gate-driven a-Si:H TFTs exhibit extremely low photo-leakage currents, much lower than that of single-gate-driven TFTs in a certain range (reverse subthreshold region) of negative gate voltages. The high on/off current ratio under backside illumination makes dual-gate TFTs suitable devices for use as switching elements in liquid-crystal displays (LCDs) or for other applications.

P‐1.17: High Performance Dual‐Gate a‐Si:H TFTs For High‐Refresh‐Rate LCDs

“…However, an additional mask for the top-metal-gate electrode limits its own application. In order to avoid extra mask, the dual-gate a-Si:H TFTs with transparent ITO top-gate electrodes were fabricated by Chang et al [8], which is compatible with the conventional BCE TFT fabrication process. The on-currents are proportional to the width of ITO top gate until the width extends to overlap the source and drain contact, while the off-currents under negative dual-gate driving bias are almost same with that of the conventional singlegate TFT.…”

The effect of the crystallization of indium tin oxide on indium tin oxide wet etching based on gate line with the structure of copper/indium tin oxide

“…The indium tin oxide (ITO) was widely used in thin film transistor-liquid crystal display (TFT-LCD), solar cells, and other optoelectronic devices due to its unique advantages, such as high transparency in visible and low resistivity. [1][2][3][4][5][6] In general, ITO was deposited as transparent pixel electrode in LCD panel by magnetron sputtering on glass. In order to realize display function, the patterning process of ITO film was necessary.…”