Fast response and multi-color photodetection in p-type Cu:CdS thin films

Abstract

We present an analysis of p-type CdS thin films deposited on glass substrates with the addition of Cu dopants. Subsequently, we explore the photodetection capabilities of the Cu:CdS/FTO heterostructure. CdS, a popular and economical photo-conducting material operating within the spectral range similar to that of the human eye, is the subject of our investigation in this work. Multicolor detection with improved sensitivity, speed, and stability remains relatively unexplored in CdS-based photodetectors. Also, the industrially beneficial spray pyrolysis technique is employed for the fabrication. Furthermore, we address the shortcomings of photodetection in the metal–semiconductor–metal structure by implementing a simple vertical heterojunction structure, p-Cu:CdS/n-FTO. Among the various Cu-doped CdS films evaluated for their optoelectronic applications, we have determined that the CdS film with a 10% Cu concentration is optimal for photodetection purposes. Low density of sulfur vacancies, proper chemical composition, and good crystallinity observed for the 10 at% Cu doped CdS film supported the excellent performance of the p-Cu_0.1Cd_0.9S/n-FTO photodetector.