The Anomalous Effect of Oxygen Ratio on the Mobility and Photobias Stability of Sputtered Zinc–Tin–Oxide Transistors

Author

Bong Seob Yang ; Seungha Oh ; Yoon Jang Kim ; Sang Jin Han ; Hong Woo Lee ; Hyuk Jin Kim ; Sungmin Kim ; Hui Kyung Park ; Jaeyeong Heo ; Jae Kyeong Jeong ; Hyeong Joon Kim

Author_Institution

Dept. of Mater. Sci. & Eng., Seoul Nat. Univ., Seoul, South Korea

Volume

61

Issue

6

fYear

2014

fDate

41791

Firstpage

2071

Lastpage

2077

Abstract

The oxygen ratio-dependent device performance and reliability of zinc tin oxide (ZTO) thin-film transistors (TFTs) were examined. ZTO TFTs fabricated under pure Ar conditions exhibited a high saturation mobility of 21.5 cm²/Vs, low subthreshold gate swing of 0.34 V/decade, and high I_ON/OFF ratio (10⁹), whereas modest mobility of 7.3 cm²/Vs was obtained for the ZTO TFTs prepared at an oxygen ratio [R = O₂/(Ar + O₂)] of 0.3. The photobias stability (AV_th ≈-2.0 V) of the ZTO TFTs under the Ar only condition was much better than that (AV_th ≈-5.9 V) of the device at R of 0.3, even though their channel layers contained the larger density of oxygen vacancies. This abnormal behavior was attributed to the compressive stress of ZTO films retarding the phototransition of oxygen vacancies.

Keywords

argon; phototransistors; semiconductor device reliability; thin film transistors; zinc compounds; Ar; TFT; ZTO thin-film transistors; ZnSnO; anomalous effect; channel layers; compressive stress; oxygen ratio; oxygen vacancy; photobias stability; phototransition; pure Ar conditions; reliability; saturation mobility; sputtered zinc-tin-oxide transistors; Compressive stress; Logic gates; Sputtering; Stability analysis; Thermal stability; Thin film transistors; Bias stress instability; film stress; light stress instability; oxygen vacancy defect; thin-film transistors (TFTs); zinc tin oxide (ZTO); zinc tin oxide (ZTO).;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/TED.2014.2318055

Filename

6809162