Investigation of two-dimensional HfS₂/PtSSe heterostructure with strong visible light adsorption and strain tunable bandgap

Abstract

Based on the first-principles calculation, the electronic structure of HfS2/PtSSe heterojunction is systematically studied. The HfS2/PtSSe heterostructure has an intrinsic type-II band alignment, with holes and electrons located at HfS2 and PtSSe, respectively. The charge distribution is well separated, which can effectively prevent carrier recombination. Compared to the isolated PtSSe and HfS2 monolayers, the light absorption of the HfS2/PtSSe heterojunction in both visible and ultraviolet regions is significantly enhanced. Furthermore, the bandgap of the heterojunction can be tuned linearly by the bi-axial strain. Especially, the heterojunction can switch from type-II to type-III band alignment at compress strain strength of -9%. The variation of the bandgap of the heterojunction is related to the increased hybridization of Hf-5d and Se-4p states under compressed strain. The adjustable bandgap indicates that the HfS2/PtSSe heterojunction is a promising high-performance adjustable optoelectronic nanodevice candidate.

Defects induced changes in conduction bands of HfS2

“…The 1T phase HfS 2 (hereinafter referred to as HfS 2 for simplicity) is a wide studied member of TMDs family, which is a semiconductor with an indirect band gap within the infra red and the visible range (∼1 − 2 eV) [16]. The room temperature carrier mobility of HfS 2 is as high as 1800 cm 2 V −1 s −1 , far exceeding the 340 cm 2 V −1 s −1 of MoS 2 [22], and it have proven to be an important candidate material for the solar energy, field-effect transistors and photovoltaics [23][24][25][26][27][28][29]. Few-layer HfS 2 FET displaying a large on/off ratio has been reported [30][31][32].…”

Pressure-induced phase transition and electronic structure evolution in layered semimetal HfTe2

“…[11,16] High-pressure is considered as a powerful tool for identifying novel behaviors of solids, [17] as pressure can signifi-cantly shorten the distance between atoms and alter their interatomic interactions and electronic bonding states, thus modifying the related physical properties and/or inducing structural phase transitions. Apart from the external electric field and the control of the thickness of the samples, [18][19][20][21] the application of pressure or strain has been demonstrated to be a desirable and clean approach in recent experimental and theoretical efforts to modify the structural framework and associated electronic properties of layered TMDs. Different pressureinduced properties of bulk TMDs have been reported, such as the band inversion and the resulting topological phase transition of TiTe 2 under pressure, [22] pressure-driven superconductivity in VSe 2 after the suppression of charge density wave (CDW), [23] the reduction of magnetoresistance in WTe 2 upon compression, [24] structural transformation accompanied with metallization in MoS 2 , TiSe 2 , MoTe 2 , etc.…”