Two types of Schottky diodes with and without thermal-growth oxide layer, were fabricated to investigate whether or not the thermal-growth oxide layer is effective on some electrical parameters such as ideality factor n, barrier height Phi(B), series resistance R-s and interface state density N-ss. The current voltage (I-V) characteristics were measured for these two diodes at 150 K and room temperature (300 K). Electrical parameters of these two diodes were calculated and compared at two temperatures. At the temperatures of 150 and 300 K, Phi(B), n, and R-s for diode without oxide layer ranged from 0.50 to 0.81 eV, 4.12 to 1.54, and 481 to 156 Omega respectively. The Phi(B), n, and R-s for diode with thermal-growth oxide layer have ranged from 0.54 to 0.87 eV, 6.83 to 1.66, and 503 to 281 Omega, respectively. For two diodes, the temperature dependence energy density distribution profiles of interface state were obtained from forward bias I-V measurements by taking into account the bias dependence of effective barrier height Phi(e) and R-s of the devices and the value of N-ss in diode without oxide layer is almost one order of magnitude larger than the diode with oxide layer. (c) 2006 Elsevier B.V. All rights reserved.