Photoelectric effect on an Al/SiO2/p-Si Schottky diode structure

Abstract

A SiO2 of 200 nm thickness layer was grown via thermal oxidation to obtain an Al/SiO2/p-Si MIS Schottky diode structure with top contacts and different active areas. Electrical measurements of MIS Schottky diode structure allow to observe the photoelectric effect only in the device with higher active area, as well as to obtain some electrical parameters such as the barrier height, the ideality factor and the density of interface states, which correspond to 0.97 eV, 1.46 and 4.44 × 1010 eV−1 cm−2 respectively. Furthermore, a fill factor of 0.202 and power conversion efficiency less than 1%. On the other hand, Capacitance-Voltage (C–V) measurements depict a positive and negative capacitance peaks at low frequencies; this behavior and photoelectric effect are attributed to the density of interface states at SiO2/p-Si, as well as to the Space-Charge-Limited Conduction process in the insulation layer. Furthermore, the use of this kind of insulator can allows increasing the conversion efficiency if it is used as bottom n-layer or front contact in tandem solar cells and silicon heterojunction solar cells, respectively.