Blackbody-sensitive room-temperature infrared detection is a notable development direction for future low-dimensional infrared photodetectors. However, because of the limitations of responsivity and spectral response range for low-dimensional narrow bandgap semiconductors, few low-dimensional infrared photodetectors exhibit blackbody sensitivity. Here, highly crystalline tellurium (Te) nanowires and two-dimensional nanosheets were synthesized by using chemical vapor deposition. The low-dimensional Te shows high hole mobility and broadband detection. The blackbody-sensitive infrared detection of Te devices was demonstrated. A high responsivity of 6650 A W⁻¹ (at 1550-nm laser) and the blackbody responsivity of 5.19 A W⁻¹ were achieved. High-resolution imaging based on Te photodetectors was successfully obtained. All the results suggest that the chemical vapor deposition–grown low-dimensional Te is one of the competitive candidates for sensitive focal-plane-array infrared photodetectors at room temperature.

We report homoepitaxial GaN growth on freestanding (11̄00) oriented (M-plane GaN) substrates using low-pressure metalorganic chemical vapor deposition. Scanning electron microscopy, atomic-force microscopy, and photoluminescence were used to study the influence of growth conditions such as the V/III molar ratio and temperature on the surface morphology and optical properties of the epilayers. Optimized growth conditions led to high quality (11̄00) oriented GaN epilayers with a smooth surface morphology and strong band-edge emission. These layers also exhibited strong room temperature stimulated emission under high intensity pulsed optical pumping. Since for III-N materials the (11̄00) crystal orientation is free from piezoelectric or spontaneous polarization electric fields, our work forms the basis for developing high performance III-N optoelectronic devices.

To improve the light extraction efficiency (LEE) of AlGaN-based deep ultraviolet LEDs (DUV-LEDs) by simple and effective method, this has greatly attracted ever-growing attention in DUV-LEDs field. Here, nanolens arrays (NLAs) fabricated by nanophotolithography and wet-etched technique is proposed to improve the LEE of DUV-LEDs, and its theoretical feasibility is verified by the Monte Carlo Ray-Trace method and finite element analysis which show an obvious improvement of light and electric field distribution benefit from NLAs structure. By controlling the time of wet etching, the effect of the uniform patterns of NLAs with adjustable morphology on the LEE of DUV-LEDs is systematically studied. Compared with the sandwiched flat lens, experimental results show that the obviously enhancements of the light output power are achieved by using the proposed NLAs to be 13.0%, 21.1%, 24.7%, 13.0%, and 11.5%, respectively, corresponding to their radius of 325, 340, 350, 360, and 400 nm, under the driving current of 300 mA. Therefore, the highest light output power of DUV-LEDs is used the optimized NLAs with radius of 350 nm, and its emission angle also shows the largest improvement of ~14°, suggesting the best LEE.

AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) suffer from severe quantum confined Stark effect (QCSE) due to the strong polarization field in the quantum wells (QWs) grown on c-plane substrates. In this work, we propose a novel DUV LED structure embedded with graded QWs in which the Al composition was linearly changed to screen the QCSE. A significant increase of the internal quantum efficiency and thus an enhancement of the light output power by nearly 67% can be achieved, attributing to the improvement of the electron-hole wave function overlap ( $\Gamma_{\rm{e}-\rm{hh}}$ ) to 58.6% in the Increased-Al-composition graded QWs, as compared to the QW without grading ( $\Gamma_{\rm{e}-\rm{hh}}$ =40.4%) and reverse grading ( $\Gamma_{\rm{e}-\rm{hh}}$ =33.6%). Further investigations show that the grading profile of the Al composition in the QWs, including either linearly increases or decreases along the growth direction and the thickness of graded QWs, determine the polarization electrical field in the QWs and as a result, significantly affecting the performance of the devices. In the end, a careful optimization of the graded QWs is called. The proposed structure with such unique graded QWs provides us an effective solution to suppress the QCSE effect in the pursuit of high performance DUV emitters.