In Situ Fabrication of CdS/ZnTe Heterojunction Diodes by Pulsed Laser Deposition

Heterojunctions made of n-type cadmium sulfide (CdS) and p-type zinc telluride (ZnTe) thin films with rectifying behavior have been developed using an in situ approach based on pulsed laser deposition (PLD). The structure of the CdS and ZnTe thin films was observed by x-ray diffraction (XRD) analysis. Optical and electrical characterization of the semiconductor films and fabricated diodes is also reported herein. For this purpose, a set of CdS/ZnTe diodes was fabricated with circular gold contacts of varying diameters from 100 µm to 300 µm. The carrier concentrations of the semiconductor layers were determined using a Hall-effect measurement system, yielding values of 5.26 × 10¹⁸ cm⁻³ and 3.5 × 10¹³ cm⁻³ for CdS and ZnTe, respectively. Current–voltage (I–V) characteristic curves were used to observe the typical rectifier behavior over three orders of magnification. In addition, other parameters were obtained from the I–V curves, such as the density current, saturation current, series resistance, threshold voltage, and ideality factor. Also, capacitance–voltage (C–V) characteristic curves allowed the determination of the following parameters: depletion width, built-in voltage, and donor concentration. According to the results, such n-type CdS/p-type ZnTe heterojunctions with rectifying behavior could find potential applications in the development of photodetectors by modifying the difference in carrier concentration between the two materials.