New trends in ZnO nanoparticles/n-Si heterojunction photodetector preparation by pulsed laser ablation in ethanol

In this paper, ZnO nanoparticles/n-Si heterojunction photodetectors were fabricated by laser ablation of zinc oxide nanoparticles NPs in ethanol solution. The effect of laser fluence on the structural, optical and electrical properties of synthesized ZnO nanoparticles was demonstrated. The optical properties showed that the ZnO has direct energy gap ranging from 3.1 to 3.35 eV depending on laser flunce. X-ray diffraction XRD results confirmed that the ZnO NPs are crystalline in nature with hexagonal wurtzite structure. Scanning electron microscope SEM investigation confirmed that synthesised ZnO particles have average size of 70-85 nm and nanoparticles agglomeration was noticed. Photoluminescence measurements show exciton UV and visible peaks emission. The dependence of electrical properties of ZnO NPs/n-Si heterojunction photodetectors on laser fluence has been studied and analyzed. All the heterojunctions exhibited good rectifying nature and ideality factor was in the range of 2.4-3.7. The spectral responsivity results showed that all photodetectors have two peaks of response located at 650 nm and 800 nm with maximum responsivity of 0.32 and 0.63 A/W, respectively without using post deposition annealing.