Temperature and humidity effects on the stability of on-plastic a-Si:H thin film transistors with various conduction channel layer thicknesses

摘要

Stability is an important issue for the application of TFTs. In this paper, we present the effects of humidity and temperature on the stability of inverted-staggered back-channel-cut a-Si:H TFTs with various conduction channel layer thicknesses. We evaluated the stability of on-plastic TFTs of different conduction layer thicknesses made at a process temperature of 150℃ on 51-μm thick Kapton polyimide foil substrates. With conduction channel layer thickness of 50nm, humidity reversibly varies the characteristics of TFTs, but TFTs of conduction layer thickness greater than 100 nm are pretty immune to the humidity change. The temperature dependent stability and characteristics of TFTs were analyzed from 20℃ to 60℃. Rising temperature from 20℃ to 56℃, the threshold voltage (V_t) drops about 2 volts; on-off current ratio decreases by one order of magnitude mainly due to thermally excited carriers in the off-region.