The Impacts of Different Electrode Structures on the Device Performance of β-(AlxGa1−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.