Density of States of a-InGaZnO From Temperature-Dependent Field-Effect Studies

Author

Chen, Charlene ; Abe, Katsumi ; Kumomi, Hideya ; Kanicki, Jerzy

Author_Institution

Dept. of Electr. Eng. & Comput. Sci., Univ. of Michigan, Ann Arbor, MI

Volume

56

Issue

6

fYear

2009

fDate

6/1/2009 12:00:00 AM

Firstpage

1177

Lastpage

1183

Abstract

Temperature-dependent field-effect measurements were performed on radio-frequency sputtered amorphous In-Ga-Zn-O thin film transistors (TFTs). We studied the effect of temperature on the TFT electrical properties. We observed that the field-effect mobility (mu) increases and the threshold voltage (V _T) shifts negatively with temperature, while the current on-off ratio and subthreshold slope (S) remain almost unchanged. We also observed that the TFT drain current (I_D) is thermally activated, and the relation between the prefactor (I_D0) and activation energy (E _a) obeys the Meyer-Neldel rule. The density of localized gap states (DOS) was then calculated by using a self-consistent method based on the experimentally obtained E _a. The result shows good agreement with the DOS distribution calculated from SPICE simulations.

Keywords

carrier mobility; electronic density of states; gallium compounds; indium compounds; localised states; semiconductor device models; sputter deposition; thin film transistors; InGaZnO; Meyer-Neldel rule; SPICE simulations; activation energy; density of localized gap states; electrical properties; field-effect mobility; radio-frequency sputtered amorphous thin film transistors; self-consistent method; temperature-dependent field-effect measurements; threshold voltage; Amorphous materials; Electrodes; Electron beams; Gold; Performance evaluation; Radio frequency; Sputtering; Temperature distribution; Temperature measurement; Thin film transistors; Activation energy; Meyer–Neldel (MN) rule; amorphous In–Ga–Zn–O (a-InGaZnO); density of localized gap states (DOS); thin film transistor (TFT);

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/TED.2009.2019157

Filename

4895299