Investigation of MgIn2O4 MSM UV Photodetector With Different Oxygen Flow Ratios and Post-Annealing Temperatures

Abstract

In this study, MgIn2O4 UV photodetectors with metal-semiconductor-metal structure were deposited by RF sputtering using a single MgIn2O4 target. The characteristics of deposited MgIn2O4 thin films as well as fabricated PDs with different oxygen flow ratios and annealing temperatures were explored. The as-deposited MgIn2O4 thin film is a transparent material with transmittance of over 75% in the visible region and the wide bandgap of above 3.9 eV, indicating MgIn2O4 is a potential candidate for UV-sensing applications. The MgIn2O4 PD with oxygen flow ratio of 2% and post-annealed at 300 °C shows the best performance due to the enhanced UV absorption and an extremely low dark current. Such device shows a dark current of 5.00 × 10−13 A, a comparable photo-to-dark current ratio of 1.82 × 107, the responsivity of 1.38 A W−1, and an UV-to-visible rejection ratio of 4.3 × 103.