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Title: Controlled ambient and temperature treatment of InGaZnO thin film transistors for improved bias-illumination stress reliability

The failure mechanisms arising from the instability in operation of indium gallium zinc oxide based thin film transistors (TFTs) upon prolonged real application stresses (bias and illumination) have been extensively studied and reported. Positive and negative gate bias conditions, along with high photonic energy wavelengths within visible light spectrum are used as stress conditions. The increased carrier concentration due to photonic excitation of defects within bandgap and ionization of deep level vacancies is compensated by the reduction in off currents under illumination due to the trapping of carriers in the intermetal dielectric. Band lowering at the source-channel junction due to accumulation of negative carriers repelled due to negative gate bias stress further causes high carrier flow into the channel and drives the devices into failure. The defect identification during failure and degradation assisted in proposing suitable low temperature post processing in specific ambients. Reliability tests after specific anneals in oxygen, vacuum, and forming gas ambients confirm the correlation of the defect type with anneal ambient. Annealed TFTs demonstrate high stabilities under illumination stresses and do not fail when subjected to combined stresses that cause failure in as-fabricated TFTs. Oxygen and forming gas anneals are impactful on the reliability and opensmore » an area of study on donor and vacancy behavior in amorphous mixed oxide based TFTs. The subthreshold swing, field-effect mobilities, and off currents provide knowledge on best anneal practices by understanding role of hydrogen and oxygen in vacancy annihilation and transistor switching properties.« less
Authors:
 [1] ;  [2] ;  [3]
  1. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe 85287 (United States)
  2. School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe 85287 (United States)
  3. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe 85287 and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe 85287 (United States)
Publication Date:
OSTI Identifier:
22258670
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 32; Journal Issue: 2; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; CARRIERS; DEFECTS; DIELECTRIC MATERIALS; ELECTRIC CONTACTS; FAILURES; GALLIUM; GALLIUM OXIDES; HYDROGEN; ILLUMINANCE; INDIUM; OXYGEN; RELIABILITY; STRESSES; TEMPERATURE RANGE 0065-0273 K; THIN FILMS; TRANSISTORS; VACANCIES; ZINC OXIDES