Preparation of low cost n-ZnO/MgO/p-Si heterojunction photodetector by laser ablation in liquid and spray pyrolysis

In this study, low cost ZnO/Si and ZnO/MgO/Si heterojunction (HJ) photodetectors were fabricated using laser ablation and spray Pyrolysis techniques. MgO nanofibers were synthesized by laser ablation of Mg target in distilled water. Also; the ZnO films were prepared by spray pyrolysis technique. The optical and structural properties of nanostructured MgO were investigated using XRD, SEM and FTIR. The XRD results showed that the MgO was polycrystalline with cubic structure. SEM investigation confirmed the formation of MgO nanofibers and sub-microparticles. The optical energy gaps of MgO and ZnO were calculated and found to be 5.7 eV and 3.3 eV, respectively. For the electrical properties; responsivity, quantum efficiency, specific detectivity, and speed of response of the photodetector were measured and found to enhance after the insertion of nanostructured MgO film. The Photo response results at 3 V reverse bias showed that the maximum responsivity of ZnO/Si and ZnO/MgO/Si photodetectors were 185 and 331 mAW(-1) at 500 nm, respectively. The specific detectivity of ZnO/ MgO / Si Photodetector was higher than that of ZnO / Si.