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 beta-Ga2O3 solar-blind photodetector, how to employ the intrinsic electric field (E-in) of 2D materials to tune the optoelectronic performance of beta-Ga2O3 devices further has not yet been demonstrated. Here, by investigating the optoelectronic properties of beta-Ga2O3/Janus-TMD heterostructures with different E(in)s, we found that the heterostructures exhibit type-I band alignment when the E-in direction points to the contact interface, whereas it demonstrates type-II band alignment for the opposite E-in 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 E-in enlarges. The band offsets of all beta-Ga2O3/Janus-TMD heterostructures can be enlarged when the E-in is enhanced by altering the chalcogens in the Janus-TMDs, whereas they are reduced when the E-in is enlarged by altering the metals. The underlying mechanisms are due to the direction and intensity of E-in for Janus-TMDs directly affecting its band levels, band bending of beta-Ga2O3 surface and charge transfer at the beta-Ga2O3/Janus-TMD interface. These findings reveal the role of E-in in asymmetrical polar 2D materials on the optoelectronic performances of beta-Ga2O3 devices, and provide a guideline to design high performance Ga2O3 optoelectronic devices. (C) 2020 The Author(s).

Automated summary

The optoelectronic properties of beta-Ga2O3/Janus-TMD heterostructures were investigated with different E(in)s, revealing the impact of E-in direction on band alignments and providing guidance for designing high-performance Ga2O3 optoelectronic devices.