Quantum dots engineered within two-dimensional materials represent a significant advancement in nanoscale semiconductor technology, combining the unique electronic properties of 2D materials with the quantum confinement effects of zero-dimensional structures. These systems, particularly those based on transition metal dichalcogenides (TMDCs) and graphene, exhibit exceptional tunability, making them promising candidates for quantum computing, single-photon emitters, and other optoelectronic applications. Unlike traditional III-V quantum dots, 2D-material-based quantum dots benefit from inherent atomic-scale thickness, strong light-matter interactions, and the ability to manipulate their properties through strain, defects, and electrostatic gating.

The electronic properties of quantum dots in 2D materials are primarily governed by quantum confinement and the reduced dielectric screening in atomically thin layers. In TMDCs such as MoS2, WS2, and WSe2, quantum dots can be formed by creating localized potential wells that trap excitons or charge carriers. The bandgap of these materials is layer-dependent, transitioning from indirect in bulk to direct in monolayers, which enhances photoluminescence efficiency. Confinement in these systems leads to discrete energy levels, analogous to atomic orbitals, with level spacings that can exceed 10 meV, depending on dot size and material composition. Graphene quantum dots, on the other hand, exhibit unique Dirac fermion physics, with edge states and size-dependent bandgaps that can be tuned from the infrared to the visible spectrum.

Fabrication techniques for quantum dots in 2D materials fall into two broad categories: top-down and bottom-up approaches. Top-down methods include lithographic patterning and etching, which can define quantum dots with precision but may introduce edge defects that affect performance. Bottom-up techniques leverage strain engineering, defect creation, and electrostatic confinement. Strain engineering, for instance, involves applying localized mechanical deformation to modulate the band structure, creating potential wells without chemical modification. Defect-induced quantum dots are formed by introducing vacancies or dopants that locally alter electronic properties. Electrostatic confinement uses patterned gates to create tunable potential landscapes, enabling dynamic control over carrier trapping.

Material systems such as TMDCs offer advantages over traditional III-V quantum dots in terms of integration and scalability. III-V quantum dots, typically fabricated via molecular beam epitaxy, are embedded in a three-dimensional matrix, making them difficult to isolate or pattern at high densities. In contrast, 2D-material quantum dots can be directly synthesized or processed on substrates compatible with silicon technology. The absence of lattice mismatch issues further simplifies heterostructure integration. Additionally, the exciton binding energy in TMDCs is an order of magnitude higher than in III-V materials, exceeding 100 meV in some cases, which enhances stability at room temperature.

Applications in quantum computing leverage the spin and valley degrees of freedom unique to 2D-material quantum dots. In TMDCs, the valley index can serve as a robust qubit basis, with optical selection rules allowing for selective excitation and readout. Single-photon emitters based on these systems exhibit high purity and indistinguishability, critical for quantum communication. The emission wavelength can be tuned via strain or electric fields, enabling spectral matching in photonic circuits. Graphene quantum dots, while lacking a natural bandgap, can be engineered to exhibit Coulomb blockade and spin qubit behavior, with coherence times that rival traditional semiconductor platforms.

Comparisons between 2D-material quantum dots and III-V systems highlight trade-offs in performance and fabrication. III-V quantum dots benefit from mature growth techniques and high reproducibility, with emission linewidths as narrow as 1 µeV at cryogenic temperatures. However, they require complex heterostructures and lack the flexibility of 2D-material systems. In contrast, 2D-material quantum dots offer on-demand tunability and easier integration but may exhibit broader linewidths due to environmental inhomogeneities. Advances in encapsulation and passivation are addressing these challenges, pushing the performance closer to that of III-V counterparts.

The future of 2D-material quantum dots lies in optimizing their properties for scalable quantum technologies. Strain engineering, combined with advanced lithography, could enable arrays of identical quantum dots with uniform emission characteristics. Hybrid systems, integrating TMDCs with photonic cavities or superconducting resonators, may enhance light-matter interaction for quantum networking. As fabrication techniques mature, these systems could surpass traditional quantum dots in both functionality and manufacturability, unlocking new paradigms in quantum information science and optoelectronics.