The effect of gate overlap lightly doped drains on low temperature poly-Si thin film transistors |
| |
Authors: | Jaehyun Cho Sungwook Jung Kyungsoo Jang Hyungsik Park Jongkyu Heo Wonbaek Lee DaeYoung Gong Seungman Park Hyungwook Choi Hanwook Jung Byoungdeog Choi Junsin Yi |
| |
Affiliation: | The School of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea |
| |
Abstract: | Low temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) have a high carrier mobility that enables the design of small devices that offer large currents and fast switching speeds. However, the electrical characteristics of the conventional self-aligned polycrystalline silicon (poly-Si) TFTs are known to present several undesired effects, such as large leakage currents, the kink effect, and the hot-carrier effect. For this paper, LTPS TFTs were fabricated, and the SiNx/SiO2 gate dielectrics and the effect of the gate-overlap lightly doped drain (GOLDD) were analyzed in order to minimize these undesired effects. GOLDD lengths of 1, 1.5 and 2 μm were used, while the thickness of the gate dielectrics (SiNx/SiO2) was fixed at 65 nm (40 nm/25 nm). The electrical characteristics show that the kink effect is reduced in the LTPS TFTs using a more than 1.5 μm of GOLDD length. The TFTs with the GOLDD structure have more stable characteristics than the TFTs without the GOLDD structure under bias stress. The degradation from the hot-carrier effect was also decreased by increasing the GOLDD length. After applying the hot-carrier stress test, the threshold voltage variation (ΔVTH) was decreased from 0.2 V to 0.06 V by the increase of the GOLDD length. The results indicate that the TFTs with the GOLDD structure were protected from the degradation of the device due to the decreased drain field. From these results it can be seen that the TFTs with the GOLDD structure can be applied to achieve high stability and high performance in driving circuit applications for flat-panel displays. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|