College of Engineering  |  Department of Electrical Engineering and Computer Science  |  ECE Division

Contact Information:
Prof. J. Kanicki
University of Michigan
EECS Department
2307 EECS Bldg.
1301 Beal Ave
Ann Arbor, MI 48109-2122

Tel: (734) 936-0964 (Office)
Tel: (734) 936-0972 (Lab)
Fax: (734) 615-2843

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Research Index

Density of States of Amorphous In-Ga-Zn-O

Linsen Bie, Kai-Chen Cheng and Jerzy Kanicki

chart1To understand the device physics of amorphous In-Ga-Zn-O (a-IGZO) and operation principles of the a-IGZO thin film transistors (TFTs), we propose a density-of-states (DOS) model of the a-IGZO based on our experiments and published results. The DOS model is further studied in the 2D numerical simulation of the a-IGZO TFT.

The DOS model of the a-IGZO is composed of four parts: conduction band tail states, sub-gap acceptor states, oxygen vacancy states and valence band tail states. We extract valence band tail states through optical analysis with a characteristic energy of 110meV. Conduction band tail states and sub-gap acceptor states are calculated from experimental data of temperature-dependent field-effect study of the a-IGZO TFT. Oxygen vacancies are thought to behave as deep donors located near the valence band. We then implement the DOS in the two dimensional numerical simulation of the a-IGZO TFT and the obtained results reveal good agreement with measured transistor electrical properties. We believe the proposed DOS model and 2D numerical simulation result will help us in better understanding of the device operation and in optimization of device electrical performance for flat panel display and imager application.




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