Filterless tunable photoconductive ultraviolet radiation detector using CeF3 thin films grown by pulsed laser deposition

We report the development of filterless deep ultraviolet photoconductive detectors using cerium fluoride (CeF3) thin films fabricated by pulsed laser deposition (PLD). By varying the PLD laser power during thin film growth, we observed that CeF3 breaks down to CeF2 at PLD laser powers greater than 100 mW. This consequently leads to the formation of fluorine defects that effectively narrowed the optical bandgap of the thin films, resulting in the decreased resistivity of the photoconductive detector. Under ultraviolet irradiation, the detector using a thin film grown at 5 mW PLD laser power exhibited close to four orders of magnitude increase in photocurrent compared to the dark current. The spectral response of the photoconductive detectors can be tuned from 300 nm to 400 nm when PLD laser powers ranging from 5 mW to 400 mW are used to fabricate the thin films. The filterless nature of the detectors simplifies their production, and their tunability can extend their use to a wider range of applications.