微晶硅材料及其薄膜晶体管的研究

摘要

本文在微晶硅材料性能研究的基础上制备了微晶硅薄膜晶体管(TFT).发现微晶硅的柱状生长模式会导致其结构和电学性能的不均匀性.由于材料的柱状生长模式使得其晶化百分比、晶粒尺寸和暗电导受到薄膜厚度的调制.平行于衬底和垂直于衬底方向的电导率随着材料沉积条件的变化呈现出不同的变化规律,后者始终保持在 10-6 s/an～10-5 s/cm 量级.确定了用于 TFT 有源层的微晶硅薄膜沉积条件中的硅烷浓度应高于 2%,晶化百分比应为40%～50%左右.制备的微晶硅 TFT 器件具有良好的稳定性,开态电流的衰退和阈值电压的漂移分别为 25%和1 Ⅴ,进而还发现了一种新颖的自恢复现象.%The Microcrystalline silicon (μc-Si: H) material performances and the obtained TFT have been investigated. It has been found that the column-like growth model of the μc-Si:H may cause the structural and electrical anisotropy of it. The crystalline volume ratio (Xc), grain size and dark conductivity are mod-ulated by the film thickness because of its column-like growth. The parallel conductivity (σ∥) and perpen-dicular conductivity (σ⊥) show different changing tendency with the variation of deposition conditions, the latter keeps on 10-5 s/cm ～10-6s /cm. Based on the investigation on the μc-Si: H material characteristics,the appropriate silicon concentration (SC) for the μc-Si: H deposition used as the active layer of TFT has been indicated, which should be higher than 2%, the Xc should be around 40～50%. The resulted μc-Si.H TFT shows a good reliability, the degradation ratio of Ⅰon and the Ⅴth shift are less than 25% and 1 Ⅴ re-spectively. Furthermore, a new recoverable instability phenomenon has also been found