Enhanced photo-response of CdTe Thin film via Mo doping prepared using electron beam evaporation technique

Abstract

CdTe and 1–5 wt% molybdenum-doped CdTe materials were prepared by ball milling method. Then the ball-milled samples were deposited on a glass substrate at room temperature by an electron beam evaporation method. The structural, optical, morphological, electrical, and photo-response properties of CdTe and Mo-doped CdTe (CdTe:Mo) samples were investigated. The prepared samples exhibit a cubic structure of CdTe. X-ray diffraction pattern (XRD) showed that the deposited films belong to the cubic structure with a preferential growth along (111) plane. The peak shift in the lower side of 2θ was observed due to incorporation of Mo into the CdTe matrix. Surface morphology of the prepared CdTe and CdTe:Mo ball-milled samples showed the formation of various agglomerated structures. Scanning electron microscope images depicted the formation of high dense agglomerated grains on the film surface with varying sizes as a function of Mo concentration. The optical bandgap was increased from 1.38 to 1.54 eV with raising the Mo concentration in CdTe films. Enhanced optical absorption coefficients (~ 17 × 104 cm−1) were observed for 3 and 4 wt% Mo doped CdTe thin films. Hall measurement studies revealed that Mo doped CdTe (3 wt%) film possesses a low resistivity of 34 × 103 Ω cm. The CdTe and CdTe:Mo films exhibit p-type conduction. The high photo-response of 0.088 AW−1 is observed for 3 wt% Mo-doped CdTe thin film.