Effect of Light Intensity and Temperature on the Current Voltage Characteristics of Al/SY/p-Si Organic-Inorganic Heterojunction

An organic-inorganic contact was fabricated by forming a thin film of sunset yellow dye (SY) on a p-Si wafer. The device showed a good rectification property, and the sunset yellow thin film modified the barrier height (Ub) of Al/p-Si contact by influencing the space charge region. The heterojunction had a strong response to the different illumination intensities and showed that it can be suitable for photodiode applications. The I-V measurements of the device were also applied in the temperature range of 100-500 K. It was seen that characteristic parameters of the device were strongly dependent upon temperature. While the value of Ub increased, the ideality factor (n) decreased with the increase in temperature. This variation was attributed to spatial inhomogeneity at the interface. The Norde function was used to determine the temperature-dependent series resistance and Ub values, and there was a good agreement with that of ln I-V data. The values of the Richardson constant (A*) and mean Ub were determined as 29.47 A cm(-2) K-2 by means of a modified activation energy plot, matching with a theoretical one, and 1.032 eV, respectively. Therefore, it was stated that the current voltage characteristic with the temperature can be explained by thermionic emission theory with Gaussian distribution of the Ub at the interface.