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

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 350ºC. Besides the measured specific detectivity at room
temperature is D*=2.31×108 cm Hz1/2W-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.