Temperature dependent electrical characteristics of Nichrome/4H-SiC Schottky barrier diodes

Nichrome Schottky barrier diodes have been fabricated on 4H-SiC substrates to investigate the temperature dependant electrical characteristics of the fabricated contacts. The electrical parameters such as barrier height, ideality factor and donor concentration were found from the current-voltage (I-V) and the capacitance-voltage (C-V) measurements at room temperature. Barrier Contacts showed non-ideal behaviour like lower value of barrier height and high value of ideality factor. A barrier height of 1.53eV obtained from C-V measurements and 0.79eV obtained from the I-V measurements with ideality factor of 1.96 for as-deposited diodes at room temperature. The diodes, therefore, were annealed in the temperature range from 25-400 ºC to see the effect of annealing temperature on these parameters. Schottky barrier height (SBH) and ideality factors were found temperature dependent. After rapid thermal annealing (RTA) upto 400 ºC barrier height of 1.27 eV from C-V measurements and the value of 1.13 eV were obtained from I-V measurements with ideality factor of 1.12. Since barrier height deduced from C-V measurements were consistently larger than those from I-V measurements. To remove this discrepancy we re-examined our results by including the effect of ideality factor in the expression of the saturation current. The insertion of ideality factor results in comparably good agreement between the values of barrier height derived by above two methods. We believe that the enhancement in the electrical parameters result from the improvement in the quality of interfacial layer.