Molybdenum disulfide (MoS₂) is one of the most important two-dimensional materials after graphene. Monolayer MoS₂ has a direct bandgap (1.9 eV) and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS₂’s synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS₂, where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS₂ films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS₂ with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS₂ with competitive quality. There is a long way to go for MoS₂ in real-life electronic device applications.

Polarization response of artificially structured nano-antennas can be exploited to design innovative optical components, also dubbed “vectorial metasurfaces”, for the modulation of phase, amplitude, and polarization with subwavelength spatial resolution. Recent efforts in conceiving Jones matrix formalism led to the advancement of vectorial metasurfaces to independently manipulate any arbitrary phase function of orthogonal polarization states. Here, we are taking advantages of this formalism to design and experimentally validate the performance of CMOS compatible Jones matrix metasurfaces monolithically integrated with standard VCSELs for on-chip spin-decoupling and phase shaping. Our approach enables accessing the optical spin states of VCSELs in an ultra-compact way with previously unattainable phase controllability. By exploiting spin states as a new degree of freedom for laser wavefront engineering, our platform is capable of operating and reading-out the spin-momentum of lasers associated with injected spin carriers, which would potentially play a pivotal role for the development of emerging spin-optoelectronic devices.

Graphene is an ideal material for wide spectrum detector owing to its special band structure, but its low light absorption and fast composite of photogenerated carriers lead to a weak response performance. In this paper, we designed a unique photoconductive graphene-InGaAs photodetector. The built-in electric field was formed between graphene and InGaAs, which can prolong the lifetime of photogenerated carriers and improve the response of devices by confining the holes. Compared with graphene-Si structure, a higher built-in electric field and reach to 0.54 eV is formed. It enables the device to achieve a responsivity of 60 AW⁻¹ and a photoconductive gain of 79.4 at 792 nm. In the 1550 nm communication band, the responsivity of the device is also greater than 10 AW⁻¹ and response speed is less than 2 ms. Meanwhile, the saturation phenomenon of light response was also found in this photoconductive graphene heterojunction detector during the experiment, we have explained the phenomenon by the capacitance theory of the built-in electric field, and the maximum optical responsivity of the detector is calculated theoretically, which is in good agreement with the measurement result.