CAPACITANCE VOLTAGE CHARACTERISTICS OF A METAL-CARBON SILICON STRUCTURE

Capacitance-voltage (C-V) characteristics of a metal(Au)-carbon-semiconductor(Si) structure are examined in the 200 Hz to 1 MHz range under accumulation and depletion. The observed frequency dependence of the C-V curves is related to the action of interface traps present at the a-C/silicon junction. The model based on that proposed by Nicollian and Goetzberger [E. H. Nicollian and A. Goetzberger, Bell. Syst. Tech. J., 1055 (1065)] is used to simulate the frequency dependence of the impedance due to the presence of interface-trapped charge in the metal-insulator-semiconductor structure. The model gives very good agreement with the experimental data. The density of the trap charge is extracted from the model and is found to be of the order of 10(10) cm-2 eV-1. Electron spin resonance measurements show a spin density of 4 x 10(18) cm-3 with a g-factor of 2.003. This is attributed to the dangling bond in carbon. Comparison of the C-V and ESR data suggests that the carbon dangling bond does not act as a trap centre at room temperature.