A Study of GSZO TFTs for Fabrication on Plastic Substrates

Abstract

Flexible electronics have many developing applications, such as liquid crystal displays (LCDs), organic lightemitting diodes (OLEDs), flex-circuits with connectors and flexible solar cells. Transparent amorphous oxide semiconductors (TAOSs) are the likely candidates to form the active layer of the pixel-driven thin film transistors (TFTs) due to their good uniformity, excellent electrical and optical properties, and compatibility with low temperature deposition. The excellent properties of indium gallium zinc oxide (IGZO) make it the prime candidate; however, the increase in demand of indium has driven up the price. Hence, cheaper substitutes for indium which can produce TAOS TFTs suitable for plastic substrates with comparable characteristics are desired. The focus of this work is on the investigation of the effect of radio frequency (RF) sputtered deposition parameters on the gallium tin zinc oxide (GSZO) based thin film transistor performance and stability. The compositional, optical and morphological properties of the films were examined using x-ray spectroscopy, x-ray reflectivity, Rutherford backscattering and optical absorption techniques. The TFTs were characterized using room temperature current - voltage and capacitance-voltage characteristics and their optical and electrical stability were examined. It was found that that the TFT performance for the GSZO channel deposition and annealing temperature below 140 deg C are sensitive to the deposition parameters. The oxygen deficient deposited films led to porous films, with high electron trap density, shallow oxygen vacancies and Zn interstitial states. The oxygen rich ambient deposition on the other hand led to smooth surface and interfaces with dense films with Sn in the desired Sn 4+ state. However, these are dominated by deep filled states. The electrical and optical stability was found to be sensitive to these deposition conditions.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2014
Accession Number
ADA611134

Entities

People

  • Robert Alston

Organizations

  • North Carolina Agricultural and Technical State University

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Band Gaps
  • Carrier Mobility
  • Chemical Vapor Deposition
  • Chemistry
  • Electrical Properties
  • Electron Mobility
  • Energy Bands
  • Fabrication
  • Flexible Electronics
  • Geometry
  • Materials
  • Measurement
  • Optical Properties
  • Organic Light Emitting Diodes
  • Scattering
  • Semiconductors
  • Thin Film Transistors

Fields of Study

  • Materials science

Readers

  • Semiconductor Device Technology
  • Thin Film Deposition Science.

Technology Areas

  • Microelectronics
  • Microelectronics - Graphene