Characterization of ZnO metal–semiconductor–metal ultraviolet photodiodes with palladium contact electrodes

ZnO metal–semiconductor–metal (MSM) photodiodes with palladium (Pd) contact electrodes were fabricated. It was found that the barrier height at the Pd/ZnO interface was 0.701 eV. With an incident wavelength of 370 nm and 1 V applied bias, it was found that the maximum responsivity of the Pd/ZnO/Pd MSM photodiodes was 0.051 A/W, which corresponds to a quantum efficiency of 11.4%. For a given bandwidth of 100 Hz and 1 V applied bias, we found that the noise equivalent power and the corresponding detectivity D * were 1.13 × 10 −12 W and 6.25 × 10 11 cmHz 0.5 W −1 , respectively.