{
  "id": "1905.02391",
  "version": "v1",
  "published": "2019-05-07T07:31:33.000Z",
  "updated": "2019-05-07T07:31:33.000Z",
  "title": "Layer degree of freedom for excitons in transition metal dichalcogenides",
  "authors": [
    "Sarthak Das",
    "Garima Gupta",
    "Kausik Majumdar"
  ],
  "journal": "Physical Review B, 99, 165411, 2019",
  "doi": "10.1103/PhysRevB.99.165411",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.mtrl-sci"
  ],
  "abstract": "Layered transition metal dichalcogenides (TMDCs) host a variety of strongly bound exciton complexes that control the optical properties in these materials. Apart from spin and valley, layer index provides an additional degree of freedom in a few-layer thick film. Here we show that in a few-layer TMDC film, the wavefunctions of the conduction and valence band edge states contributing to the K (K') valley are spatially confined in the alternate layers - giving rise to direct (quasi-)intra-layer bright exciton and lower-energy inter-layer dark excitons. Depending on the spin and valley configuration, the bright exciton state is further found to be a coherent superposition of two layer-induced states, one (E-type) distributed in the even layers and the other (O-type) in the odd layers. The intra-layer nature of the bright exciton manifests as a relatively weak dependence of the exciton binding energy on the thickness of the few-layer film, and the binding energy is maintained up to 50 meV in the bulk limit - which is an order of magnitude higher than conventional semiconductors. Fast stokes energy transfer from the intra-layer bright state to the inter-layer dark states provides a clear signature in the layer-dependent broadening of the photoluminescence peak, and plays a key role in the suppression of the photoluminescence intensity observed in TMDCs with thickness beyond monolayer.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-05-07T07:31:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "transition metal dichalcogenides",
      "layer degree",
      "bright exciton",
      "band edge states contributing",
      "valence band edge states"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Phys. Rev. B"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}