Interfacial Charge Transfers and Carrier Regulation Characteristics of Narrow/Wide Band Gap Tmds@Ga2o3 N-N Heterojunction Film

Abstract

Transition metal dichalcogenides (TMDs) with unique layered structure and interesting electronic properties, which has the narrower band-gap and high electron-hole recombination rate, limiting its application in many optical devices. The combination of wide and narrow is an excellent strategy that facilitates carrier separation. However, the interface interaction and charge transfer under photo excitation of wide and narrow TMDs/Ga 2 O 3 heterostructures still needs to be discussed. Herein, the WSe 2 /Ga 2 O 3 and MoS 2 /Ga 2 O 3 composite films were successfully prepared with uniformity by two-step radiofrequency magnetron sputtering method. The growth mechanism and interface charge transfer of wide and narrow TMDs/Ga 2 O 3 heterostructures are observed. The X-ray diffraction results show that the (002) orientation of the WSe 2 and MoS 2 is suppressed, which is related to the variation in the thickness. The A 1g of TMDs in heterostructures is blue-shifted in Raman spectra compared to pure TMDs, which suggesting the density of electronic states decrease. Interface charge transfer under the built-in electric field and the conversion from trions recombination to exciton recombination indicates that the carriers of TMDs are separated. Effective charge separation not only reduces energy loss but also significantly enhances nonlinear optical response. It is confirmed that Ga 2 O 3 is a promising candidate for enhancing the saturable absorption or reverse saturable absorption process of TMDs by an open-aperture Z-scan measurement.

Keywords: TMDs/Ga2O3heterointerface, Interfacial charge transfer, The nonlinear absorption, Z-scan