Adjustable electronic properties of PtSe2/HfS2 heterostructures via strain engineering

Abstract

2D PtSe2 Semiconductors are promising for the development of next-generation infrared photodetectors. However, the performance of 2D PtSe2 photodetectors is largely limited by their small detection range (due to large bandgap) and poor light absorption (due to indirect bandgap). To overcome these limitations, vertical PtSe2/HfS2 van der Waals heterostructures were constructed and the rule of their electronic property changes under strain was investigated systematically. The heterostructures exhibit type-II band alignment and a smaller bandgap (E(PtSe2) − E(PtSe2/HfS2) = 1.19 eV), which is beneficial for the separation of carriers and the application in infrared photodetectors. Moreover, the stacking configurations do not change the type of band alignment, and the bandgap of different stackings are similar, which proves that the electronic properties of the heterojunction are stable. Among the six stackings, AA stacking is the most stable structure, which can be modified to adapt to different working conditions under strain. It exhibits a quasi-direct bandgap (0.14 eV) under the condition of 11% reverse strain applied in × and Y directions respectively, which is suitable for preparing photoelectric devices working in the middle and far infrared regime. These findings provide a theoretical basis for the application of PtSe2/HfS2 heterojunction in next-generation infrared photodetectors.