Al doped tin oxide (Al:SnO2)(1) are fabricated onto silicon substrate by easy spray pyrolysis route. The room temperature current-voltage (I-V) measurements of Ag/Al:SnO2/n-Si/Au junction are taken under dark and various illumination level. The reverse and forward current increase with the increasing of illumination intensity, gradually. The device exhibits good photodiode properties but a photovoltaic behavior is not observed. Ideality factor values is found to be 7.54 and 5.41 two distinct linear region of the I-V curve of the junction under dark. Its value varies between 4.87 and 5.80 under light. The zero-bias barrier height decreases with increasing illumination level. The value of series resistance obtained from generalized Norde plot have showed a strong dependence on illumination level. Its value is calculated as 1.83 k Omega and 0.91 k Omega under dark and illumination level of 190 mW/cm(2), respectively. The space limited current (SCLC) conduction mechanism is investigated under dark and light conditions. The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of the junction are analyzed in a wide range of applied voltage (from -8 V to + 8 V). The thickness of Al:SnO2 thin film is obtained as 360 nm by using C and G data at 1 MHz and 8 V.