Two-dimensional semiconductor

Geim and Novoselov et al. initiated the field in 2004 when they reported a new semiconducting material graphene, a flat monolayer of carbon atoms arranged in a 2D honeycomb lattice.

One issue regarding graphene is its lack of a band gap, which poses a problem in particular with digital electronics because it is unable to switch off field-effect transistors (FETs).

When exfoliated into monolayers, the band gaps of several TMDCs change from indirect to direct,[7] which lead to broad applications in nanoelectronics,[3] optoelectronics,[8][9] and quantum computing.

[10] While exfoliated TMDC monolayers exhibit promising optoelectronic properties, they are often limited by intrinsic and extrinsic defects,[11] such as sulfur vacancies and grain boundaries, which can negatively affect their performance.

To address these issues, various chemical passivation techniques, including the use of superacids and thiol molecules,[12] have been developed to enhance their photoluminescence and charge transport properties.

Additionally, phase[13] and strain engineering[14] have emerged as powerful strategies to further optimize the electronic characteristics of TMDCs, making them more suitable for advanced applications in nanoelectronics and quantum computing.

In 2008 cadmium selenide CdSe quasi 2D platelets were first synthesized by colloidal method with thicknesses of several atomic layers and lateral sizes up to dozens of nanometers.

[28] Testing these materials is more challenging that their bulk counterparts, with methods employing the use of scanning probe techniques such as atomic force microscopy (AFM).

[6] Theoretical work has predicted the control of the band edges hybridization on some van der Waals heterostructures via electric fields and proposed its usage in quantum bit devices, considering the ZrSe2/SnSe2 heterobilayer as an example.

The interlayer exchange interaction is relatively weak, a magnetic field on the order of 0.5 T in the out-of-plane (𝒛) direction can induce spin-flip transition in bilayer CrI3.

Monolayer graphene
Layered structure of h-BN
Layered structure of MoS 2 , Mo in green, S in yellow
CVD setup for MoS 2 synthesis
Proposed TMDC-based high-electron-mobility transistor device with top-gated Schottky contact and TMDC layers with different doping levels. [ 36 ]
Proposed vdW qubit composed of ZrSe 2 /SnSe 2 . The electrode V G applies the vertical electric field, changing the state of the electron in the conduction band, represented by the green Bloch sphere. Zr, Sn, and Se in red, blue, and gray, respectively. [ 10 ]