Background and key features

Hydrogenated amorphous silicon Thin Film Transistors (TFTs) suffer from low carrier mobility and poor threshold voltage (V_th) stability. However, this is not an issue for pixel driving because the TFT operating duty cycle is very low. Integration of driving circuitry or OLED pixel addressing circuits is thus problematic as far as operating duty cycle becomes high. Polycristalline silicon TFTs could overcome these limitations but processing technologies as laser assisted crystallisation are not easily scalable at a low cost of ownership and this technology is restricted to niche markets.