Van der Waals (vdW) heterostructures are the fundamental blocks for two-dimensional (2D) electronic and optoelectronic devices. In this work, a high-quality 2D metal–semiconductor NiTe2/MoS2 heterostructure is prepared by a two-step chemical vapor deposition (CVD) growth. The back-gated field-effect transistors (FETs) and photodetectors based on the heterostructure show enhanced electronic and optoelectronic performance than that of a pristine MoS2 monolayer, owing to the better heterointerface in the former device. Especially, this photodetector based on the metal–semiconductor heterostructure shows 3 orders faster rise time and decay time than that of the pristine MoS2 under the same fabrication procedure. The enhancement of electronic behavior and optoelectronic response by the epitaxial growth of metallic vdW layered materials can provide a new method to improve the performance of optoelectronic devices.

Spin-orbit coupling plays an important role in the spin Hall effect and topological insulators. Bose-Einstein condensates with spin-orbit coupling show remarkable quantum phase transition. In this work we control an exciton polariton condensate – a macroscopically coherent state of hybrid light and matter excitations – by virtue of the Rashba-Dresselhaus (RD) spin-orbit coupling. This is achieved in a liquid-crystal filled microcavity where CsPbBr3 perovskite microplates act as the gain material at room temperature. Specifically, we realize an artificial gauge field acting on the CsPbBr3 exciton polariton condensate, splitting the condensate fractions with opposite spins in both momentum and real space. Besides the ground states, higher-order discrete polariton modes can also be split by the RD effect. Our work paves the way to manipulate exciton polariton condensates with a synthetic gauge field based on the RD spin-orbit coupling at room temperature.

Perovskite materials such as CsPbBr3 attract intensive attention due to excellent photonic properties. Especially, the exciton polariton condensate based on perovskite CsPbBr3 has been realized at room temperature. In this work, we observe the XY splitting of exciton polaritons localized in disorder induced potential traps in a CsPbBr3 microcavity due to the anisotropy of the perovskite and polariton condensation onto the horizontally and vertically linear polarized modes. In addition, the refractive index of the microcavity can be modified by filling liquid crystal molecules into the cavity layer, which can modify the XY splitting of localized polaritons. Our results pave the way to study the nontrivial band structure based on the XY splitting of the localized polariton condensate in microcavities.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have great potential applications in the electronic and optoelectronic devices. Nevertheless, due to the difficulty in the efficient doping of atomic-thickness TMDCs or Fermi level pinning (FLP) effects at the metal/semiconductor interface, most TMDC devices exhibit the n-type conduction polarity, which significantly limits their functional applications based on the p–n junction. Here, 2D semi-metal NiTe2 nanosheets were epitaxially grown on the WS2 monolayer by a two-step chemical vapor deposition route. The microstructure and optical characterizations confirm that the vertically stacked NiTe2/WS2 heterostructures are formed by van der Waals epitaxy. Interestingly, p-type WS2 field-effect transistors can be obtained with the hole mobility of ∼4.22 cm2/V·s, when the epitaxial NiTe2 sheets act as the source/drain electrodes. This is attributed to the decreased FLP effect and hence the low potential barrier for holes at the van der Waals contacts. Furthermore, the photodetectors based on the heterostructures show a 2 orders of magnitude increase in the switch ratio, responsivity, and detectivity and a 1 order of magnitude increase in the rise and decay speeds relative to those based on pristine WS2. This work paves the way to realize the p-type contact for monolayer WS2 with significantly enhanced optoelectronic performance.