Microstructural and optical properties of Ga-doped ZnO semiconductor thin films prepared by sol-gel process

Chien Yie Tsay, Chun Wei Wu, Chien Ming Lei, Fan Shiong Chen, Chung Kwei Lin

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Abstract

Transparent thin films of Ga-doped ZnO (GZO), with Ga dopant levels that varied from 0 to 7 at.%, were deposited onto alkali-free glass substrates by a sol-gel process. Each spin-coated film was preheated at 300 °C for 10 min, and then annealed at 500 °C for 1 h under air ambiance. The effects of Ga dopant concentrations on crystallinity levels, microstructures, optical properties, and electrical resistivities of these ZnO thin films were systematically investigated. Photoluminescence spectra of GZO thin films were examined at room temperature. XRD results revealed that the undoped ZnO thin films exhibited a preferred orientation along the (002) plane and that the ZnO thin films doped with Ga showed degraded crystallinity. Experimental results also showed that Ga doping of ZnO thin films could markedly decrease surface roughness, improve transparency in the visible range, and produce finer microstructures than those of undoped ZnO thin films. The most promising films for transparent thin film transistor (TTFT) application produced in this study, were the 3 and 5 at.% Ga-doped ZnO thin films, both of which exhibited an average transmittance of 90.6% and an RMS roughness value of about 2.0 nm.

Original languageEnglish
Pages (from-to)1516-1520
Number of pages5
JournalThin Solid Films
Volume519
Issue number5
DOIs
Publication statusPublished - Dec 30 2010
Externally publishedYes

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Keywords

  • Ga-doped ZnO
  • Photoluminescence
  • Sol-gel process
  • Transparent oxide semiconductor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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