ZnO:Al/c-Si (1 1 1) isotype heterojunction photodetectors were fabricated by a chemical spray pyrolysis technique. High responsivity and good junction characteristics were obtained after post-deposition rapid thermal annealing (RTA). Dark and illuminated I-V characteristics were measured and analyzed. The ideality factor was deduced from I-V characteristics and found to be 1.3 after RTA. C-V measurements revealed that the junction was abrupt type. The energyband diagram, based on the Anderson model, was constructed from the electrical properties of the junction. Good photoresponses in UV and visible regions with responsivity were around 0.1 A W −1 and 0.47 A W −1 , respectively. The rise time of the detector was improved after RTA and found to be 50 ns. These results suggest that the Al dopant could be a good choice to fabricate the doped ZnO/Si devices for photodetection and other optoelectronic applications. We describe here the fabrication process and optoelectronic characteristics of the photodetector.

Spray pyrolysis deposition technique has been used to grow ZnO thin films doped with different dopant species (Al, Cu, I). The optical and electrical properties of films were investigated as function of dopant type and concentration. The structural characteristics of undoped and doped ZnO films were studied using X-ray diffraction (XRD). The electrical resistivity as low as 4 × 10 −2 Ωcm was obtained for ZnO:Al with 5 at.% dopant concentration. ZnO:Cu films prepared at specific conditions exhibited p-type conductivity. The optical band gap of doped ZnO films varied from 3.09 eV to 3.2 eV. XRD investigation confirmed that the doped ZnO films had preferred orientation in the direction of (101) plane.