Negative gate bias stress effects on conduction and low frequency noise characteristics in p-type poly-Si thin-film transistors

• 来源期刊: 中国物理B（英文版）
• 关键词: polycrystalline silicon thin film transistor negative bias stress low frequency noise
• 年，卷（期）: 2019,（8）
• 页码范围: 397-402
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/1674-1056/28/8/088502

摘要

The instability of p-channel low-temperature polycrystalline silicon thin film transistors (poly-Si TFTs) is investigated under negative gate bias stress (NBS) in this work.Firstly,a series of negative bias stress experiments is performed,the significant degradation behaviors in current-voltage characteristics are observed.As the stress voltage decreases from -25 V to-37 V,the threshold voltage and the sub-threshold swing each show a continuous shift,which is induced by gate oxide trapped charges or interface state.Furthermore,low frequency noise (LFN) values in poly-Si TFTs are measured before and after negative bias stress.The flat-band voltage spectral density is extracted,and the trap concentration located near the Si/SiO2 interface is also calculated.Finally,the degradation mechanism is discussed based on the current-voltage and LFN results in poly-Si TFTs under NBS,finding out that Si-OH bonds may be broken and form Si* and negative chargeOH-under negative bias stress,which is demonstrated by the proposed negative charge generation model.