An experimental and theoretical analysis of the effect of irradiation time to Gamma ray on the SnO₂/n-Si hetero-junction devices have been carried out. The time of exposure to Gamma ray was taken as (t= 0, 50, 100, and 150 min.) at room temperature. The power intensity of illumination was 9.5 mw/cm2. Increasing irradiation time led to increase in photo current. We estimate theoretical model for this effect to obtain (J –V) curve for any irradiation time that we do not take experimentally. “Table curve 2D, version 5.01” program was used to make the fitting curve for all experimental data. The best estimated theoretical equation was :Y= a + b x +c ex. Theoretical (J- V) curve has been achieved for test irradiation time (t= 75 and 125 min.) and plotted with experimental data, there is a good similarity between them. In this work we have demonstrated an experimental study and theoretical analysis of the effect of power intensity of illumination on the SnO2/n-Si Heterojunction devices that have been irradiated with Cs 137 for 150 min. Gamma ray. The (J-V) characteristic was plotted as function of power intensity of illumination (1.95, 2.88, 3.78, 5.9, and 9.5) mw/cm2. There was an increase in efficiency of this device until maximum efficiency reached at 9.5 mw/cm2 represents optimal case. Theoretical analysis of this process was achieved by using “Table Curve 2D version 5.01” program leading to estimate theoretical modeling equation : Y= a + b x +c ex. We have calculated these parameters (a, b, and c) as function of power intensity and tested the equation for power intensity (4 and 8 mw/cm2). Theoretical (J- V) curves have been plotted with experimental data. There is a good agreement between them and the behavior of these two curves contains linear term and exponential term.
