The effect of series resistance and oxide layer formed by thermal oxidation on some electrical parameters of Al/SiO2/p-Si Schottky diodes

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 ΦB, series resistance Rs and interface state density Nss. 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, ΦB, n, and Rs for diode without oxide layer ranged from 0.50 to 0.81 eV, 4.12 to 1.54, and 481 to 156 Ω respectively. The ΦB, n, and Rs 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 Ω, 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 Φe and Rs of the devices and the value of Nss in diode without oxide layer is almost one order of magnitude larger than the diode with oxide layer.