Effect of light illumination on threshold voltage and sub-threshold slope of amorphous silicon thin film transistors

Lihong Jiao, Christopher R. Wronski, Thomas Nelson Jackson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In this study the light induced defect state creation under 1 sun illumination is investigated through changes in sub-threshold slope, Δ, and threshold voltage, V T, in a-Si:H TFT structures. Threshold voltage changes can be due to either charge trapping or defect state creation near the interface of gate insulator and a-Si:H active layer. The charge trapping effects have been minimized by incorporating high quality thermal silicon dioxide in the a-Si:H TFT, and the changes in threshold voltage can be attributed to induced defect states in the a-Si:H. Since the sub-threshold current is closely related to the band gap defect states, both V T and Δ can be used as a new probe to study the light induced defect creation in the a-Si:H. The information obtained about the nature of gap defect states from the analysis of changes in V T and Δ under light illumination is presented. The results obtained show that under 1 sun illumination there are very fast increases (within 10 seconds) in V T with subsequent slow increases and no observable changes in Δ, similar to those observed in the light induced photoconductivity changes in a-Si:H thin films. Results are also presented on changes in V T under gate-bias stress. Comparisons are then made between the results obtained under 1 sun light illumination and those under gate-bias stress. The information obtained in this study about the nature of the gap defect states derived from characterization of the sub-threshold regimes is discussed.

Original languageEnglish (US)
Title of host publicationAmorphous and Polycrystalline Thin-Film Silicon Science and Technology - 2006
Pages467-472
Number of pages6
Volume910
StatePublished - 2007
Event2006 MRS Spring Meeting - San Francisco, CA, United States
Duration: Apr 18 2006Apr 21 2006

Other

Other2006 MRS Spring Meeting
CountryUnited States
CitySan Francisco, CA
Period4/18/064/21/06

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

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    Jiao, L., Wronski, C. R., & Jackson, T. N. (2007). Effect of light illumination on threshold voltage and sub-threshold slope of amorphous silicon thin film transistors. In Amorphous and Polycrystalline Thin-Film Silicon Science and Technology - 2006 (Vol. 910, pp. 467-472)