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Title: Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

Abstract

In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

Authors:
; ; ;  [1]
  1. School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22402441
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM; LAYERS; OXIDES; OXYGEN; PERFORMANCE; THIN FILMS; TRANSISTORS; ZINC

Citation Formats

Ahn, Cheol Hyoun, Hee Kim, So, Gu Yun, Myeong, and Koun Cho, Hyung, E-mail: chohk@skku.edu. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition. United States: N. p., 2014. Web. doi:10.1063/1.4901732.
Ahn, Cheol Hyoun, Hee Kim, So, Gu Yun, Myeong, & Koun Cho, Hyung, E-mail: chohk@skku.edu. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition. United States. doi:10.1063/1.4901732.
Ahn, Cheol Hyoun, Hee Kim, So, Gu Yun, Myeong, and Koun Cho, Hyung, E-mail: chohk@skku.edu. Mon . "Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition". United States. doi:10.1063/1.4901732.
@article{osti_22402441,
title = {Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition},
author = {Ahn, Cheol Hyoun and Hee Kim, So and Gu Yun, Myeong and Koun Cho, Hyung, E-mail: chohk@skku.edu},
abstractNote = {In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.},
doi = {10.1063/1.4901732},
journal = {Applied Physics Letters},
number = 22,
volume = 105,
place = {United States},
year = {Mon Dec 01 00:00:00 EST 2014},
month = {Mon Dec 01 00:00:00 EST 2014}
}
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