Effect of fabrication variables on the performance of zinc oxide metal-semiconductor-metal photodetectors

The performance of ZnO metal-semiconductor-metal (MSM) photodetectors can be significantly influenced by modifications in the fabrication process. ZnO thin films were deposited onto silicon substrates by radio frequency magnetron sputtering and later annealed by conventional furnace, rapid thermal anneal or laser anneal. The photoluminescence (PL) analysis revealed that laser annealing at 250 mW/cm² increased the 370 nm peak from 520 to 1700 a.u. and reduced the defect peak from 380 to 20 a.u. MSM photodetectors were fabricated using an interdigitated and parallel pattern. Values of current responsivity ranged from about 0.025 A/W to above 430 A/W depending upon fabrication conditions and design.