Transition metal dichalcogenides (TMDs) (MX 2 , M = Mo or W, X = S, Se, or Te) have attracted intense interest for developing ultrascaled electronics and optoelectronics by virtue of their attractive 2D layered structures and unique physical properties that are absent in their bulk counterparts. [1][2][3][4][5] Monolayer semiconducting TMDs show sizable direct bandgaps, quantum confinement effects, large exciton binding energies and effective valley polarizations, which unveils widespread applications in field-effect transistors (FETs), photodetectors, light-emitting diodes, pumped lasers, solar cells, and valleytronic devices. [6][7][8][9][10] More excitingly, their 2D structures offer superior electrostatic controllability and exemptible short-channel effects, rendering TMDs promising candidates for future sub-10 nm complimentary metal-oxide-semiconductor (CMOS) devices. [5,11,12] The applications of exfoliated TMD flakes in building high-performance prototypes of electronics, photonics, and optoelectronics have already been demonstrated. [13][14][15][16] The exfoliated flakes, however, suffer from Monolayer MoTe 2 , with the narrowest direct bandgap of ≈1.1 eV among Mo-and W-based transition metal dichalcogenides, has attracted increasing attention as a promising candidate for applications in novel near-infrared electronics and optoelectronics. Realizing 2D lateral growth is an essential prerequisite for uniform thickness and property control over the large scale, while it is not successful yet. Here, layer-by-layer growth of 2 in. wafer-scale continuous monolayer 2H-MoTe 2 films on inert SiO 2 dielectrics by molecular beam epitaxy is reported. A single-step Mo-flux controlled nucleation and growth process is developed to suppress island growth. Atomically flat 2H-MoTe 2 with 100% monolayer coverage is successfully grown on inert 2 in. SiO 2 /Si wafer, which exhibits highly uniform in-plane structural continuity and excellent phonon-limited carrier transport behavior. The dynamics-controlled growth recipe is also extended to fabricate continuous monolayer 2H-MoTe 2 on atomic-layer-deposited Al 2 O 3 dielectric. With the breakthrough in growth of wafer-scale continuous 2H-MoTe 2 monolayers on device compatible dielectrics, batch fabrication of high-mobility monolayer 2H-MoTe 2 field-effect transistors and the three-level integration of vertically stacked monolayer 2H-MoTe 2 transistor arrays for 3D circuitry are successfully demonstrated. This work provides novel insights into the scalable synthesis of monolayer 2H-MoTe 2 films on universal substrates and paves the way for the ultimate miniaturization of electronics.

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Epitaxially grown semiconductor quantum dots are promising candidates for pure single photon and polarization-entangled photon pair emission. Excellent optical properties can typically be ensured only if these so-called “artificial atoms” are buried deep inside the semiconductor host material. Quantum dots grown close to the surface are prone to charge carrier fluctuations and trap states on the surface, degrading the brightness, coherence, and stability of the emission. We report on high-purity single photon emission [g(2)(0) = 0.016 ± 0.015] of GaAs/AlGaAs quantum dots that were grown only 20 nm below the surface. Chemical surface passivation with sulfur compounds such as octadecanethiol has been performed on quantum dots with 20, 40, and 98 nm from the surface. The reduction of the density and influence of surface states causes improvements in linewidth and photoluminescence intensity as well as a well-preserved single photon emission. Therefore, the realization of hybrid nanophotonic devices, comprising near-field coupling and high-quality optical properties, comes into reach.

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