“…If the valley polarization is unperturbed by even stronger lateral confinement, ML TMD nanostructures might be a viable platform for exploring the valley degrees of freedom of a single electron 20 . The techniques required to achieve strong lateral confinement in smaller patterned monolayer nanostructures and the new quantum phenomena and edge effects that would arise in this regime 19 , 26 , 27 are beyond the scope of this work.…”
Section: Discussionmentioning
confidence: 99%
“…The robustness of valley polarization to lateral confinement in ML TMDs remains an open fundamental question with implications for valley control schemes (Fig. 1b,c) 19, 25–27 .Figure 1( a ) Patterning of a 2D semiconductor into laterally-confined ML nanodots. ( b ) 2D confinement of excitons of Bohr radius a
B in a potential well of radius R .…”
Three-dimensional confinement allows semiconductor quantum dots to exhibit size-tunable electronic and optical properties that enable a wide range of opto-electronic applications from displays, solar cells and bio-medical imaging to single-electron devices. Additional modalities such as spin and valley properties in monolayer transition metal dichalcogenides provide further degrees of freedom requisite for information processing and spintronics. In nanostructures, however, spatial confinement can cause hybridization that inhibits the robustness of these emergent properties. Here, we show that laterally-confined excitons in monolayer MoS2 nanodots can be created through top-down nanopatterning with controlled size tunability. Unlike chemically-exfoliated monolayer nanoparticles, the lithographically patterned monolayer semiconductor nanodots down to a radius of 15 nm exhibit the same valley polarization as in a continuous monolayer sheet. The inherited bulk spin and valley properties, the size dependence of excitonic energies, and the ability to fabricate MoS2 nanostructures using semiconductor-compatible processing suggest that monolayer semiconductor nanodots have potential to be multimodal building blocks of integrated optoelectronics and spintronics systems.
“…If the valley polarization is unperturbed by even stronger lateral confinement, ML TMD nanostructures might be a viable platform for exploring the valley degrees of freedom of a single electron 20 . The techniques required to achieve strong lateral confinement in smaller patterned monolayer nanostructures and the new quantum phenomena and edge effects that would arise in this regime 19 , 26 , 27 are beyond the scope of this work.…”
Section: Discussionmentioning
confidence: 99%
“…The robustness of valley polarization to lateral confinement in ML TMDs remains an open fundamental question with implications for valley control schemes (Fig. 1b,c) 19, 25–27 .Figure 1( a ) Patterning of a 2D semiconductor into laterally-confined ML nanodots. ( b ) 2D confinement of excitons of Bohr radius a
B in a potential well of radius R .…”
Three-dimensional confinement allows semiconductor quantum dots to exhibit size-tunable electronic and optical properties that enable a wide range of opto-electronic applications from displays, solar cells and bio-medical imaging to single-electron devices. Additional modalities such as spin and valley properties in monolayer transition metal dichalcogenides provide further degrees of freedom requisite for information processing and spintronics. In nanostructures, however, spatial confinement can cause hybridization that inhibits the robustness of these emergent properties. Here, we show that laterally-confined excitons in monolayer MoS2 nanodots can be created through top-down nanopatterning with controlled size tunability. Unlike chemically-exfoliated monolayer nanoparticles, the lithographically patterned monolayer semiconductor nanodots down to a radius of 15 nm exhibit the same valley polarization as in a continuous monolayer sheet. The inherited bulk spin and valley properties, the size dependence of excitonic energies, and the ability to fabricate MoS2 nanostructures using semiconductor-compatible processing suggest that monolayer semiconductor nanodots have potential to be multimodal building blocks of integrated optoelectronics and spintronics systems.
“…In recent years, study of magnetic properties of QDs has attracted much attention among researchers . For instance, Kumar et al and Boda et al have numerically investigated the effects of electron‐electron (e‐e) interaction and spin‐orbit coupling on magnetic susceptibility of a parabolic InAs and GaAs QD, respectively.…”
In this work, we study three-electron magnetic susceptibility in quantum dots under Rashba spin-orbit interaction (SOI) and magnetic field by an analytical methodology.The Hamiltonian of the system is separated to center of mass and relative terms using the Jacobi transformations and the hyperspherical coordinates. By solving Schrodinger equation, energy levels and thereby the susceptibility are calculated using canonical ensemble. At zero temperature, the magnetization reduces with increasing magnetic field with and without Rashba SOI in three-electron-quantum dot without electron-electron (e-e) interaction. Also, SOI slightly changes the magnetization for three-electron-quantum dot without e-e interaction. At nonzero temperature, the magnetization shows a paramagnetic peak when the magnetic field increases. This peak position changes under the SOI. In the presence of e-e interaction, the susceptibility enhances with raising magnetic field and it shows a maximum.The susceptibility at low magnetic field is negative and then it becomes positive.The susceptibility with e-e interaction and without SOI is always diamagnetic and its magnitude reduces with enhancing magnetic field. The susceptibility shows a transition between diamagnetic and paramagnetic with e-e interaction and SOI.
K E Y W O R D Selectron-electron interaction, magnetization, quantum dot, Rashba spin-orbit interaction
“…Theoretical research on electronic properties of MoS 2 and other TMDQDs has included tight‐binding (TB), [ 41–43 ] first‐principles density functional (DFT) theory [ 44–48 ] approaches, for different geometrical structures such as triangular and hexagonal. Several proposals for a Slater–Koster TB description of TMD MLs and multilayers appeared in 2013.…”
A theoretical investigation on electronic states in triangular MoS2 quantum dots of different sizes is performed within density functional theory first‐principles formalism. Herein, the associated interband optical response from real and imaginary parts of the dielectric function is calculated. The study considers both undoped and Al‐, Si‐, and P‐doped systems. Spin‐related magnetic properties are considered through the evaluation of total magnetic moment. It is revealed that small enough structures have a semiconductor character, but evolve to seemingly half‐metallic with increasing dot size. Nonzero magnetic response is attributed to edge effects. Magnetic behavior of doped systems deviates from the linear dependence of the total magnetic moment with size occurring in the undoped case, producing situations with higher total momentum values. It is found that increasing the doping density may have certain influence over total magnetic moment response of the structures, although edge dominance is kept all the way. Optical properties are not as sensitive to incident light polarization, but they actually do with regard to the particular spin orientation. Calculation for the refraction index in the triangular quantum dots shows values still below the accepted in the MoS2 monolayer case, although a correct trend of variation is reported in this sense.
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