Effect of post-deposition processing on ZnO thin films and devices

Post-deposition processing was conducted on ZnO thin films deposited by radio frequency (RF) magnetron sputtering. Rapid thermal annealing (RTA) and ion implantation followed by RTA gave increased conductivity and the latter increased Hall-effect mobility from 1.7 cm ₂ V ^-1 s ^-1 to 9.5 cm ² V ^-1 s ^-1 Metal-semiconductor-metal photodetectors (MSM-PDs) had a low dark current, a high ratio of photo to dark current, and a high responsivity of 2.1 A/W. Current transport mechanisms of MSM-PDs with post-annealing exhibited two primary space-charge-limited mechanisms, m > 2 and m < 1, following I ≈ V ^m. The non-annealed ZnO film gave one mechanism with m < 1 in photo I-V. Response to a femtosecond pulse gave rise and fall times in the range of 12 ns to 29 ns.