Low temperature fabrication of amorphous silicon thin film transistors by dc reactive magnetron sputtering

C. S. McCormick, C. E. Weber, J. R. Abelson, G. A. Davis, R. E. Weiss, V. Aebi

Research output: Contribution to journalArticlepeer-review

Abstract

We deposit hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon nitride (a-SiNx:H) films using dc reactive magnetron sputtering at 125 and 230°C substrate temperatures. We characterize the structural properties using infrared absorption, thermal hydrogen evolution, and refractive index measurements, and evaluate the electrical quality using capacitance-voltage and leakage current measurements. Nitride layers deposited at both temperatures have dominant N-H bonding with hydrogen concentration approximately 1022/cm3. Metal-insulator-semiconductor devices have been fabricated on c-Si and show electrical leakage of < 5 X 10-8 A/cm2 at 3 MV/cm field, flat band voltage magnitude < 1 V, and hysteresis < 2 V. Low temperature a-Si:H films show monohydride dominant bonding. The photo- to dark conductivity ratio is 5 X 105 for films deposited at 125°C. Inverted staggered thin film transistors have been fabricated with the optimized layers. Thin film transistors deposited at 230°C have a field effect mobility of 0.8 cm2/V s, an Ion/Ioff ratio of 5 X 105, a subthreshold slope of 1.2 V/decade, and a threshold voltage of 4 V; those deposited at 125°C have a field effect mobility of 0.3 cm2/V s, an Ion/Ioff ratio of 5 X 105, and a threshold voltage of 3 V.

Original languageEnglish (US)
Pages (from-to)2770-2776
Number of pages7
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume15
Issue number5
DOIs
StatePublished - 1997

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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