Estimation of the interface states density of a Si/C{sub 60} heterojunction by frequency-dependent capacitance{endash}voltage characteristics
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113 (Japan)
Capacitance{endash}voltage (C{endash}V) characteristics of a Si/C{sub 60} heterojunction, i.e., a HF solution (7.3{percent} HF+30{percent} NH{sub 4}F) treated Si surface interfaced solid crystal of C{sub 60} molecules, were measured while applying various ac frequencies. The entire C{sub 60} thin film and near-interface region of the Si wafer behaved as a depletion region, with the C{endash}V curve showing two distinct regions: one above and one below a threshold bias voltage. Below the threshold, C{endash}V characteristics were dependent on applied frequency, which suggests the presence of interface states that only affect capacitance at lower frequencies. This frequency dependence was analyzed by assuming a suitable equivalent circuit, and based on derived curve-fitting circuit parameters the interface states density was accordingly estimated to have a value as low as {approximately}10{sup 11}/cm{sup 2}eV. Such a small density indicates that only a few lattice defects occur within the interface of the HF-treated Si surface and C{sub 60} crystal. Although no frequency dependence was observed above the threshold, the C{endash}V characteristics were found to be dependent on the width of the depletion region in Si. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 544317
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 9; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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