Capacitance analyses of hydrogenated nanocrystalline silicon based thin film transistor

ANUTGAN T., ANUTGAN M., Atilgan I., Katircioglu B.

THIN SOLID FILMS, vol.519, no.11, pp.3914-3921, 2011 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 519 Issue: 11
  • Publication Date: 2011
  • Doi Number: 10.1016/j.tsf.2011.01.284
  • Journal Name: THIN SOLID FILMS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.3914-3921
  • Middle East Technical University Affiliated: Yes


The capacitance-voltage (C-V) measurements within 10(6)-10(-2) Hz frequency range were performed on the hydrogenated nanocrystalline silicon (nc-Si:H) bottom-gate thin film transistor (TFT) and metal-insulator-amorphous silicon (MIAS) structure, mechanically isolated from the same TFT. It was found that the conducting thin layer in nc-Si:H film expands the effective capacitor area beyond the electrode in the TFT structure, which complicates its C-V curves. Considering the TFT capacitance-frequency (C-F) curves, the equivalent circuit of the TFT structure was proposed and mechanism for this area expansion was discussed. On the other hand, the MIAS C-F curves were fitted by the equivalent circuit models to deduce its electrical properties. nc-Si:H neutral bulk effect was revealed by the dependence of the MIAS capacitance on frequency within 10(6)-10(3) Hz at both accumulation and depletion regimes. The inversion in MIAS was detected at 10(2)-10(-2) Hz for relatively low negative gate bias without any external activation source. The presence of the ac hopping conductivity in the nc-Si:H film was inferred from the fitting. In addition, the density of the interface traps and its energy distribution were determined. (C) 2011 Elsevier B.V. All rights reserved.