ZnO:Ca MSM ultraviolet photodetectors

Photoresponse of calcium doped zinc oxide (ZnO:Ca) metal-semiconductor-metal (MSM) UV detectors are reported. Photosensitive ZnO:Ca films exhibit high transparency in the visible region, show polycrystalline, hexagonal wurtzite structure, having c-axis preferred growth. Noticed redshift of 60 meV in the optical band gap for ZnO:Ca (3 wt%) thin film is attributed to increased crystallite size. Improved n-type conductivity in ZnO with Ca doping is due to increased carrier concentration, MSM photodetector fabricated with, 3 wt% Ca doped ZnO exhibit higher responsivity of 3.05A/W at 365 nm UV illumination. Transient response measurements show reasonably fast switching with a rise and fall time of 15s and 26s respectively. The obtained results suggest, ZnO: Ca can be used as active material in the fabrication of UV photodetectors.

Automated summary

The photoresponse of calcium-doped zinc oxide (ZnO:Ca) metal-semiconductor-metal (MSM) UV detectors is investigated. The ZnO:Ca films exhibit high transparency in the visible region and have polycrystalline, hexagonal wurtzite structure with preferred growth along the c-axis. The redshift in the optical band gap is attributed to increased crystallite size, resulting in improved n-type conductivity and higher responsivity for the fabricated MSM photodetector. Transient response measurements show fast switching behavior. These findings suggest that ZnO:Ca can be a promising active material for UV photodetectors.