Tuning the intrinsic electric field of Janus-TMDs to realize high-performance β-Ga2O3 device based on β-Ga2O3/Janus-TMD heterostructures

Although two-dimensional (2D) transition metal dichalcogenides (TMDs) have been employed for improving the optoelectronic performance of a β-Ga2O3 solar-blind photodetector, how to employ the intrinsic electric field (Ein) of 2D materials to tune the optoelectronic performance of β-Ga2O3 devices further has not yet been demonstrated. Here, by investigating the optoelectronic properties of β-Ga2O3/Janus-TMD heterostructures with different Eins, we found that the heterostructures exhibit type-I band alignment when the Ein direction points to the contact interface, whereas it demonstrates type-II band alignment for the opposite Ein direction. Compared with the former, the latter possesses more stability, stronger charge transport efficiency, higher optical absorption, and lower exciton binding energy, which are further improved as the intensity of the Ein enlarges. The band offsets of all β-Ga2O3/Janus-TMD heterostructures can be enlarged when the Ein is enhanced by altering the chalcogens in the Janus-TMDs, whereas they are reduced when the Ein is enlarged by altering the metals. The underlying mechanisms are due to the direction and intensity of Ein for Janus-TMDs directly affecting its band levels, band bending of β-Ga2O3 surface and charge transfer at the β-Ga2O3/Janus-TMD interface. These findings reveal the role of Ein in asymmetrical polar 2D materials on the optoelectronic performances of β-Ga2O3 devices, and provide a guideline to design high performance Ga2O3 optoelectronic devices.