Spin/Valley Coupled Dynamics of Electrons and Holes at the MoS₂–MoSe₂ Interface

Abstract

The coupled spin and valley degrees of freedom in transition metal dichalcogenides (TMDs) are considered a promising platform for information processing. Here, we use a TMD heterostructure MoS2-MoSe2 to study optical pumping of spin/valley polarized carriers across the interface and to elucidate the mechanisms governing their subsequent relaxation. By applying time-resolved Kerr and reflectivity spectroscopies, we find that the photoexcited carriers conserve their spin for both tunneling directions across the interface. Following this, we measure dramatically different spin/valley depolarization rates for electrons and holes, ~30 ns -1 and <1 ns -1 , respectively and show that this difference relates to the disparity in the spin-orbit splitting in conduction and valence bands of TMDs. Our work provides insights into the spin/valley dynamics of free carriers unaffected by complex excitonic processes and establishes TMD heterostructures as generators of spin currents in spin/valleytronic devices.

Extrinsic Localized Excitons in Patterned 2D Semiconductors

“…[8,9] These states may play a determining role in the relaxation of excitons in TMD heterostructures by providing pathways for excitations to tunnel between two angle-mismatched TMDs. [7,10] Some localized states behave as single quantum emitters, driving the interest in potential applications in quantum technologies. [6,9,11,12] More recently, single quantum emitters based on localized states in TMDs came under intense scrutiny.…”

Recent progress in 2D hybrid heterostructures from transition metal dichalcogenides and organic layers: properties and applications in energy and optoelectronics fields

“…59 Another unique feature of monolayer 2H-TMDs is that they exhibit broken inversion symmetry that results in a large valley splitting in the energy band and a strong spin valley coupling. 60 This may allow for electrical and magnetic manipulation of charge carriers in spin-based devices. In addition, the layered nature of TMDs provides distinct advantages for energy applications.…”

NaCl-Assisted Temperature-Dependent Controllable Growth of Large-Area MoS2 Crystals Using Confined-Space CVD

“…12 All of these applications of MoS 2 rely heavily on the size, shape, and crystallinity of the crystal. The electronic structure of MoS 2 can be tuned with the thickness of the crystals, which can be used for applications like spin−valley coupling 13 and abundant excitons. 14 One of the methods of obtaining 2D MoS 2 is mechanical exfoliation, which is not compatible with industrial-scale manufacturing.…”