High Performance Dual Gate Blue Laser Annealed Poly-Si Thin-Film Transistor for High-Resolution Displays

Abstract

We report a dual gate (DG), low-temperature polysilicon (LTPS) thin-film transistor ( TFT) using blue laser annealing (BLA) of amorphous silicon. The DG TFTs with variable bottom gate lengths (LBG) from 2 to 8 mu m and a fixed top gate length (LTG) of 6 mu m are investigated. The drain currents of the DG LTPS TFT with LBG > LTG by 2 mu m under DG sweep (DS) are similar to 4.3 times those of the single gate TFT. The high carrier concentrations (similar to 10(19) cm(-3)) at both interfaces (top gate insulator(GI)/poly-Si and poly-Si/bottom GI) under DS is confirmed by technology computer-aided design (TCAD) simulation, which might lead to high drain currents. The poly-Si layer exhibits no grain boundary protrusion from the transmission electron microscopy (TEM) cross-sectionalmicrograph and thus induces a strong bulk accumulation effect under DS. The fabricated DG TFT-based ring oscillator (RO) and shift register (SR) exhibit an excellent oscillation frequency of 15.8MHz, fast- rising and falling time of 370 and 366 ns at a driving voltage of -10 V, respectively.