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Polarized light has promising applications in biological inspections, displays, and precise measurements. Direct emission of polarized light from a semiconductor device is highly desired in order to reduce the size and energy-consumption of the whole system. In this study, we demonstrate a semipolar GaN-based microcavity light-emitting diode (MCLED) that could simultaneously produce green light with perpendicular and parallel polarizations to the c*-axis. Orthogonally polarized emission with a narrow linewidth (∼0.2 nm) arises from the valence band splitting and birefringent nature of the semipolar GaN material, as well as the mode selection of the resonant cavity. By modulating the cavity length, the device is capable of switching between single- and multi-mode emission spectra. We believe that the approach of employing a cavity structure and semipolar GaN can be extended to produce orthogonally and linearly polarized blue, red, and violet light by adjusting the material compositions.

Ga2O3‐based Ultraviolet‐C photodetector (UVCPD) is considered the most promising UVCPD at present and is divided into Metal‐Semiconductor‐Metal (MSM) and PN junction types. Compared with MSM‐PDs, PN‐PDs exhibit superior transient performance due to the built‐in electric field. However, current Ga2O3‐based PN‐PDs lack consideration for carrier collection and electric field distribution. In this study, PN‐PDs with an interdigital n‐Ga2O3 layer and finger electrodes are fabricated on p‐GaN/n‐Ga2O3 epilayers. Ultrafast response times of 31 µs (1/e decay) and 2.76 µs (fast component) are realized, which outperforms all Ga2O3 UVC‐PDs up to now. Under 0 V self‐powered, the responsivity (0.25 A W−1) of interdigital PD is enhanced by the interdigital electrode structure due to increasing carriers' collection length. Under bias, the performances of interdigital PD with 41.7 A W−1 responsivity and 8243 selection ratios are significantly elevated by enhancing the built‐in electric field in the Ga2O3 region, which is 34.76 and 39.4 times those of traditional PDs, respectively. The intrinsic enhancing mechanism of interdigital structure is also investigated by interdigital PDs with various electrode spacings and perimeters. In summary, this paper not only reports a highly performed interdigitated structure p‐GaN/n‐Ga2O3 UVCPDs, but also provides guidelines for structure design in Ga2O3‐based PN‐PDs. [ABSTRACT FROM AUTHOR]

Relying on a reverse energy transfer mechanism between erbium (Er3+) and ytterbium (Yb3+) ions, optical gains at wavelengths of 1550, 980, and 1067 nm are achieved in NaYF4: Er3+, and Yb3+ nanoparticles‐doped polymer waveguides under excitation of low‐power light‐emitting diodes (LEDs) instead of 976 or 1480 nm semiconductor laser as pump sources. The optical gains at 1550, 980, and 1067 nm are demonstrated in five waveguide structures: active‐rectangular, evanescent‐field with and without an aluminium (Al) reflector, and dual‐active hybrid with and without an Al reflector. The maximum relative optical gains of 6.6, 4.0, and 3.8 dBcm−1 are realized at 1550, 1067, and 980 nm, respectively, in a 5 mm long dual‐active hybrid waveguide with cross‐section of 4 × 10 µm, and a ≈100 nm‐thick Al reflector grown under the lower cladding layer under excitation of a 395 nm LED. This work proves the feasibility of using a low‐cost LED to realize multi‐wavelength amplification in a dense wavelength‐division multiplexing system and is thus valuable for the development of complex multi‐functional photonic‐integrated‐module mixed‐band optical communication systems. [ABSTRACT FROM AUTHOR]

In this paper, we report the exciton polaritons in both positive and negative detuning micro cavities based on InGaN multi-quantum wells (MQWs) and the first polariton lasing in InGaN/GaN MQWs at room temperature by utilizing a 4.5λ Fabry-Perot (F-P) cavity with double dielectric distributed Bragg reflectors (DBRs). Double thresholds corresponding respectively to polariton lasing and photonic lasing are observed along with half-width narrowing and peak blue-shifts. The threshold of polariton lasing is about half of the threshold of photonic lasing. Our results paved a substantial way for ultra-low threshold lasers and room temperature Bose-Einstein Condensate (BEC) in nitride semiconductors.

Polarized light has promising applications in biological inspections, displays, and precise measurements. Direct emission of polarized light from a semiconductor device is highly desired in order to reduce the size and energy-consumption of the whole system. In this study, we demonstrate a semipolar GaN-based microcavity light-emitting diode (MCLED) that could simultaneously produce green light with perpendicular and parallel polarizations to the c*-axis. Orthogonally polarized emission with a narrow linewidth (∼0.2 nm) arises from the valence band splitting and birefringent nature of the semipolar GaN material, as well as the mode selection of the resonant cavity. By modulating the cavity length, the device is capable of switching between single- and multi-mode emission spectra. We believe that the approach of employing a cavity structure and semipolar GaN can be extended to produce orthogonally and linearly polarized blue, red, and violet light by adjusting the material compositions. [ABSTRACT FROM AUTHOR]

Based on the molecular energy transfer mechanism, relative gains at 1067 and 637 nm wavelengths are achieved in thermally activated delayed fluorescence molecule AQ(PhDPA)2 and Nd complex with chelating phosphine oxide as ligands codoped polymer waveguides, with the excitation of low‐power UV light‐emitting diodes (LEDs) instead of traditional semiconductor lasers as pump sources. For AQ(PhDPA)2‐Nd(DBTTA)3(DBFDPO) (DBTTA = dibenzotetrathienoacene, DBFDPO = 4,6‐bis (diphenylphosphoryl) dibenzofuran) ‐codoped polymethylmethacrylate (PMMA), and AQ(PhDPA)2‐Nd(DBTTA)3(FDPO) (FDPO = 9,9‐bis (diphenylphosphorylphenyl) fluorene)‐codoped PMMA polymers with a mass ratio of 1:4 respectively, when they are spin‐coated as upper claddings, the relative gains of 2.2 and 1.8 dB cm−1 at 1067 nm are obtained in evanescent‐field waveguides with cross‐section of 4 × 8 µm2 under excitation of 300 mW 405 nm LED, and the gains of 3.9 and 4.9 dB cm−1 at 637 nm are achieved with pumping of 530 mW 450 nm LED respectively. By growing a 100 nm‐thick aluminum reflector with the waveguides, the optical gain at 1067 and 637 nm can be enhanced to 3.5 and 6.1 dB cm−1, corresponding to AQ(PhDPA)2‐Nd(DBTTA)3(DBFDPO) and AQ(PhDPA)2‐Nd(DBTTA)3(FDPO)‐codoped PMMA polymers, respectively. [ABSTRACT FROM AUTHOR]

Since the emerging development of CsPbBr3 perovskite, chemical vapor deposition (CVD) has become one of the most promising fabrication techniques by which to precisely deposit uniform perovskite thin films. However, there have been few reports on the growth dynamics and chemical reaction parameters (e.g., activation energy) for perovskite CVD. In this work, different deposition rates of CVD-grown CsPbBr3 thin films were obtained at different substrate temperatures. Dynamics equations were developed to relate the inflow rates, desorption coefficients and concentrations of reactants on the substrates. Only a small amount of reactant became activated at low temperature and a small amount of PbBr2 resided on the substrate at high temperature, and accordingly the maximal deposition rate was achieved at 250 °C. The Arrhenius activation energy of CVD-grown CsPbBr3 was also calculated, and found to be 31.64 kJ mol−1. We believe that our work provides a detailed picture of perovskite CVD growth. [ABSTRACT FROM AUTHOR]

The anisotropy of X‐ray diffraction scanning of (201) β‐Ga2O3 bulk material has been investigated. Symmetric rocking curves (RCs) exhibit distinctly different broadening along different azimuths, with a maximum along [102] and a minimum along a direction rotated by 30° from [010]. Williamson–Hall analysis was applied to study possible factors causing the broadening in these RCs, including instrumental factors, mosaic tilt and coherent scattering. It was found that the RC broadening is determined by both isotropic mosaic tilt and anisotropy in the length over which the crystal structure is not disrupted by limiting factors such as grain boundaries or stacking faults, which we term the 'lateral limited size'. In this case, the lateral limited size is governed by {200} stacking faults along the [102] direction and grain boundaries along the [010] direction. The result presents a new anisotropy characteristic of (201) β‐Ga2O3. [ABSTRACT FROM AUTHOR]