微晶硅薄膜晶体管稳定性研究

对有源区处于结构过渡区的微晶硅底栅薄膜晶体管，测试其偏压衰退特性时，观察到一种“自恢复”的衰退现象.当栅和源漏同时施加10 V的偏压时，测试其源-漏电流随时间的变化，发现源-漏电流先衰减、而后又开始恢复上升的反常现象.而当采用栅压为10 V、源-漏之间施加零偏压的模式时，源-漏电流随时间呈先是几乎指数式下降、随之是衰退速度减缓的正常衰退趋势.就此现象进行了初步探讨.关键词：过渡区硅材料微晶硅薄膜晶体管稳定性自恢复衰退

Investigation on stability of microcrystalline silicon thin film transistors

Instability of a bottom gate microcrystalline silicon (μc-Si) thin film transistor (TFT), of which the active layer was deposited by very high frequency-plasma enhanced chemical vapor deposition with silane concentration of 4% diluted by H₂, was measured and compared under two different gate bias stress conditions. A new instability phenomenon of TFT under the voltage bias stress of V_gs=V_ds=10 V was found, where the ratio of the source-drain current of μc-Si TFT to its initial value decreases first, then stays flat for a period of time, then increases. However, under the voltage bias stress of V_gs=10 V(V_ds＝0 V), the source-drain current of μc-Si TFT decreases as normal exponential decay. Analysis on the change of sub-threshold swing S and threshold voltage V_th with stress time indicated the recoverable degradation could have resulted from the electron trapping and releasing in μc-Si TFT treated by gate-bias stress with V_ds≠0.