Integrated conventional and laser re-crystallised amorphous silicon thin film transistors for large area imaging and display applications

Abstract

In this paper we present experimental data on the integration of conventional high quality bottom gate amorphous silicon (a-Si) thin film transistors (TFTs), together with devices recrystallised by an excimer laser, both on the same glass substrate. The maximum substrate temperature is 350°C and the same gate dielectric and silicon layers are used for both types of transistors. The recrystallised a-Si devices, now poly-Si TFTs, only require one extra masking step and have field-effect mobilities around 20–30 cm2/Vs, threshold voltages of 0–3 Volts, with leakage currents of 10−12 A/μm at 10V drain to source bias, while the amorphous devices remain essentially unchanged by the recrystallization process. We demonstrate the viability of the integration of these devices for use in large area arrays.