The Impacts of Different Electrode Structures on the Device Performance of β-(Al_xGa_1−x)₂O3/Ga₂O₃ Heterostructure Metal–Semiconductor–Metal Photodetectors

The effects of different electrode structures on the device performance of $\beta $ –(AlxGa1−x)2O3/Ga2O3 heterostructure metal-semiconductor–metal photodetectors (MSM PDs) have been investigated via the 2-D numerical simulation, which was developed on the basis of the modified continuity equation, transport equation, and Poisson equation. Numerical simulations were performed on the planar-type $\beta $ -Ga2O3, $\beta $ -(AlxGa1-x)2O3, MgZnO/ZnO, and $\beta $ -(AlxGa1-x)2O3/Ga2O3 MSM PDs and anode recessed InGaN/GaN MSM PD and compared with the corresponding experimental data so as to confirm the correctness of our model. Then, the current-voltage, responsivity, and detectivity characteristics of the $\beta $ -(AlxGa1-x)2O3/Ga2O3 heterostructure MSM PDs with different electrode structures, such as planar electrodes, recessed anodes, and recessed anodes and cathodes, were numerically calculated and analyzed for symmetric/asymmetric electrode materials and widths. Results showed that the recessed electrode structures could effectively enhance the photocurrents of proposed devices without significantly increasing the dark currents, and the photo-dark current ratios of recessed-type $\beta $ -(AlxGa1-x)2O3/Ga2O3 PDs could be up to $10^{{5}}$ . It was also noted that the recessed-type $\beta $ -(AlxGa1-x)2O3/Ga2O3 PDs with asymmetric electrode materials exhibit exceptionally high detectivity of over $10^{{17}}$ Jones. This work would benefit the research and development of $\beta $ -(AlxGa1-x)2O3/Ga2O3 heterostructure MSM PDs.