Study of Electrical Properties of Photodetector

In this paper porous silicon sample that can be used as a photodetector was prepared at fixed etching time of 15min and different etching current density (15, 17, 19 and 21) mA/cm2 . Electrical properties of Al / PSi / p-Si /Al photodetector were studied. We found that the I-V characteristics dependence of the etching current density relates to the PSi pores development, where the pore diameter in PSi structure might get enlarged due to the enhancement of the etching current density. The ideality factor ranges around (6.8-4.2) while the barrier height decreased with the increasing etching current density and the etching time as the interface layer between PSi/c-Si has large amount of pinning. Then the C-V characteristics of the sandwich structure are described. When the etching current densities are increased, it reduces the capacitance of the PSi layer. It thus increases the thickness of the depletion region which in turn results in development of built-in potential.