Transition metal dichalcogenides (TMDCs) represent a novel and sustainable material basis for ultrathin optoelectronic devices. Although various approaches toward light-emitting devices, e.g., based on exfoliated or chemical vapor deposited (CVD) TMDC monolayers, have been reported, they all suffer from limited scalability and reproducibility required for industrial fabrication. Here, we demonstrate a light-emitting device in a scalable approach by embedding metal−organic (MO-)­CVD WS2 monolayers into a vertical p–i–n device architecture using organic and inorganic injection layers. Red electroluminescence is emitted from an active area of 6 mm2 starting already at a driving voltage of about 2.5 V.

A detailed discussion of the optical properties of Al-rich Al 1−x In x N alloy films is presented. The (0001)-oriented layers with In contents between x = 0.143 and x = 0.242 were grown by metal-organic vapor phase epitaxy on thick GaN buffers. Sapphire or Si(111) served as the substrate. High-resolution X-ray diffraction revealed pseudomorphic growth of the nearly lattice-matched alloys; the data analysis yielded the composition as well as the in-plain strain. The complex dielectric function (DF) between 1 and 10 eV was determined from spectroscopic ellipsometry measurements. The sharp onset of the imaginary part of the DF defines the direct absorption edge, while clearly visible features in the high-photon energy range of the DF, attributed to critical points of the band structure, indicate promising crystalline quality of the AlInN layers. It is demonstrated that the experimental data can be well reproduced by an analytical DF model. The extracted characteristic transition energies are used to determine the bowing parameters for all critical points of the band structure. In particular, strain and the high exciton binding energies for the Al-rich alloys are taken into account in order to assess the splitting between the valence band with Γ v 9 symmetry and the Γ c 7 conduction band at the center of the Brillouin zone. Finally, the compositional dependence of the high-frequency dielectric constants is reported.

transition metal dichalcogenides (TMDCs) are seen as promising candidates for flexible electronic and optoelectronic devices due to their high tensile strength and favorable optical properties. Molybdenum disulfide (MoS 2 ) is a benchmark material for TMDCs, which has already been studied extensively. Here, we report on highly responsive flexible few-layer MoS 2 photodetectors based on MoS 2 synthesized uniformly for full coverage of 2 in. sapphire wafers using metalorganic vapor-phase epitaxy (MOVPE). Device performance is studied by electro-optical characterization. Electrostatic gating allows tuning both the responsivity between 150 and 920 A/W and the specific detectivity between almost 10 12 and 10 10 Jones. The measured spectrally resolved responsivities of the detectors suggest applications in the blue-light range, with opportunities for fine-tuning the most sensitive wavelength through gating, as shown through optical simulations. Finally, the flexible devices were bent to demonstrate their suitability for flexible electronics in fields of future Internet of Things and medical devices.

Enhancement-mode devices are in the centre of current research on group-III nitride transistors. The realisation of high-performance enhancement-mode transistors via gate recessing requires damage-free processing. We report on enhancement-mode AlGaN/GaN-on-Si heterostructure field-effect transistors (HFETs) fabricated with a damage-free digital etch technique. The threshold voltage (Vth) achieved is as high as +0.5 V. For AlGaN/GaN-on-Si HFETs, a record extrinsic transconductance (gm) of 420 mS/mm and a record maximum drain current Idmax of 500 mA/mm have been demonstrated. Furthermore, proper turn-off characteristics have been realised. Pulsed I–V characteristics reveal nearly no current collapse.

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