CdS Nanostructured Thin Films Synthesized by Pulsed Laser Deposition for Solar Cell Technology

Abstract

CdS thin films have been grown on glass substrate at 250o C employing pulsed laser deposition method. The effect of laser pulses number on the crystalline structure, surface morphology, optical properties, and films thickness have been studied. XRD analysis shows that the CdS films have polycrystalline and hexagonal nanostructure with three notable peaks along (100), (002), and (101) planes and preferentially orientated along (101). The crystallite size of the preferred orientation was in the range of (21.4 - 27.3 nm). With small pulses number, XRD pattern confirms the formation of CdO with three peaks (111), (200), and (220). Theses peaks gradually reduce with the increasing of the pulses. The absorbance of the films is in the visible part of the spectrum. The band gap of the synthesized films reduces by rising the number of laser pulses. AFM studies indicate that the grain size and surface roughness increase with the film thickness. Due to the good crystalline structure and optical properties of the film of the highest thickness, it has been grown on a wafer silicon substrate for solar cell applications measurements. Hall measurements indicate low resistivity of 0.3×10-2 (Ω.m) and high conductivity of 3.3×10+2 (Ω.m)-1. The efficiency of the n-CdS/ p-Si junction has been calculated to be 3.4 % using I-V characteristic measurement. Keywords: pulsed laser, thin films, structural, optical, morphology, solar cell measurements