Study of device instability of bottom-gate ZnO transistors with sol-gel derived channel layers

Kosala Yapabandara, Vahid Mirkhani, Muhammad Shehzad Sultan, Burcu Ozden, Min P. Khanal, Minseo Park, Shiqiang Wang, Michael C. Hamilton, Yoonsung Chung, Dong Joo Kim, Mobbassar Hassan Sk

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Abstract

In this paper, the authors report the device instability of solution based ZnO thin film transistors by studying the time-evolution of electrical characteristics during electrical stressing and subsequent relaxation. A systematic comparison between ambient and vacuum conditions was carried out to investigate the effect of adsorption of oxygen and water molecules, which leads to the creation of defects in the channel layer. The observed subthreshold swing and change in field effect mobility under gate bias stressing have supported the fact that oxygen and moisture directly affect the threshold voltage shift. The authors have presented the comprehensive analysis of device relaxation under both ambient and vacuum conditions to further confirm the defect creation and charge trapping/detrapping process since it has not been reported before. It was hypothesized that chemisorbed molecules form acceptorlike traps and can diffuse into the ZnO thin film through the void on the grain boundary, being relocated even near the semiconductor/dielectric interface. The stretched exponential and power law model fitting reinforce the conclusion of defect creation by oxygen and moisture adsorption on the active layer.

Original languageEnglish (US)
Article number03D104
JournalJournal of Vacuum Science and Technology B: Nanotechnology and Microelectronics
Volume35
Issue number3
DOIs
StatePublished - May 1 2017

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

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