A Wide Infrared Tuning Range of the Bulk CdSe Doped with Cu Photodetector

Hassan H. Mohammed; Salwan K. J. Al-Ani

Hassan H. Mohammed Department of Computer Engineering Technology, Iraq University College, Alestiqlal Street, Basrah, Iraq.
Salwan K. J. Al-Ani Department of Physics, College of Science, Al-Mustansiriya University, Baghdad, Iraq.

Keywords: CdSe:Cu, photodetector, infrared, tuning range, detectivity

Abstract

In this work, the adopted method of the CdSe doped with Cu (CdSe: Cu) photodetector is presented. This detector is prepared by vacuum evaporation of CdSe films on a glass substrate followed by vacuum annealing under an argon atmosphere for doping with copper. The detector is found, for the first time, to cover a wide range of the infrared besides the visible region of the electromagnetic spectrum. This finding of the wavelength tuning is due to the localized energy states of copper atoms inside the band gap of the CdSe. These characteristics stem from the unique band structure of CdSe: Cu. This tuning is compared with recent work in the corresponding colloidal CdSe-ZnS core shell quantum dots and with the quantum well (QWIR) and quantum dots infrared detectors (QDIR). The major significance of this developed detector is in its synthesis simplicity and its fabrication processes costs in comparison with that of the (QWIR) and (QDIR) detectors. The structural analysis results demonstrated that the vacuum annealing in competition with the doping concentration improves significantly the film structure. A better crystalline structure is reported at 5 wt% of Cu concentration and at annealing temperature of 350C. Besides the measured specific detectivity at room temperature is D*=2.310⁸ cm Hz^1/2W^-1. This value approaches the detectivity of the state of art mercury cadmium telluride (MCT). This result paves the way for further investigations and improvements.