关键词: 非晶硅/
薄膜晶体管/
低频噪声/
局域态密度
English Abstract
Low-frequency noise in hydrogenated amorphous silicon thin film transistor
Liu Yuan1,2,He Hong-Yu3,4,
Chen Rong-Sheng2,
Li Bin2,
En Yun-Fei1,
Chen Yi-Qiang1
1.Science and Technology on Reliability Physics and Application of Electronic Component Laboratory, CEPREI, Guangzhou 510610, China;
2.School of Microelectronics, South China University of Technology, Guangzhou 510640, China;
3.School of Electronic and Computer Engineering, Peking University Shenzhen Graduate School, Shenzhen 518005, China;
4.School of Electrical Engineering, University of South China, Hengyang 421001, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 61574048), the Science and Technology Research Project of Guangdong, China (Grant No. 2015B090912002), and the Pearl River S&T Nova Program of Guangzhou, China (Grant No. 201710010172).Received Date:17 April 2017
Accepted Date:25 August 2017
Published Online:05 December 2017
Abstract:Low-frequency noise in the hydrogenated amorphous silicon thin film transistor is investigated in this paper. The drain current noise spectral density shows a 1/fγ (γ ≈ 0.92, f represents frequency) behavior which ascribes to fluctuations of the interfacial trapped charges due to the dynamic trapping and de-trapping of free carriers into slow oxide traps and localized traps. The normalized noise has the power law dependence on overdrive voltage, and the power law coefficient is about -1 which illustrates that the flicker noise is dominated by mobility fluctuation mechanism. By considering the contact resistance, and emission and trapping processes of carriers between localized states in the Si/SiNx interface, the variation of low frequency noise with drain current is analyzed and fitted by use of the theory of carrier number fluctuation with correlated mobility fluctuation (ΔN-Δμ model). Furthermore, the relationship between surface band-bending and gate voltage is extracted based on subthreshold current-voltage characteristics, and thus the density of localized states is then extracted through the measurement of drain current noise power spectral density. The experimental results show an exponential localized state distribution in the band-gap while densities of two defect modes at the bottom of conduction band NT1 and NT2 are about 6.31×1018 and 1.26×1018 cm-3·eV-1, and corresponding characteristic temperatures TT1 and TT2 are about 192 and 290 K, which is similar to the reported distribution of tail states in the amorphous silicon layer. Finally, the average Hooge's parameter is extracted to estimate the quality of devices and materials.
Keywords: amorphous silicon/
thin film transistor/
low-frequency noise/
density of localized state
