Effect of various PCBM doping on the interfacial layer of Al/PCBM:ZnO/p-Si photodiodes

Abstract

The light can be detected by various devices such as photoconductors, photodetectors, phototransistors, solar cells, and photodiodes, and the light can be employed energy harvesting as well as sensing applications. Various materials can be utilized to raising of the efficiency of light-based devices. In this present study, metal–semiconductor (MS) devices with various [6,6]-Phenyl C61-butyric acid methyl ester (PCBM)-doped zinc oxide (ZnO) interfacial layer were fabricated for photodiode applications. Commercially purchased PCBM and ZnO were mixed in order to obtain undoped, 3%, 5%, and 10% PCBM-doped ZnO interfacial layer for Al/PCBM:ZnO/p-Si devices. The obtained solutions were layered on the p-type silicon (p-Si) substrates by spin-coating method. The thermal evaporation technique was utilized to deposit Al metal electrodes both back and front sides. The morphological properties of the fabricated devices were characterized by AFM. The morphological images of the AFM revealed that PCBM doping affected the surface morphology as well as surface roughness of the ZnO layers. I–V measurements were carried out in the dark and under varying illumination conditions for electrical properties. The devices exhibited good rectifying properties at around 103 rates, both dark and various illumination conditions, according to I–V graphs. The junction parameters of the produced devices were determined by using thermionic emission, Norde, and Cheung models from the I–V characteristics of the devices. The devices have high ideality factors, and these values generally fluctuate with varying PCBM-doping amounts. The current transient measurements show that PCBM doping provide increasing in the light response capacity. According to the results, the devices can be employed as photodiode and photodetector applications for the further works in the industry.