The fabrication of a low current bidirectional driven violet p-GaN/n-InN heterojunction light-emitting diode (LED) by the radio-frequency (RF) magnetron sputtering is reported in this paper. The indium nitride (InN) films grown at different substrate temperatures were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-2600 spectrophotometer and Hall test system, and the optimum substrate temperature was found to be 250 degrees C. The bidirectional electroluminescence (EL) behavior and the luminescence mechanism of the diode have been investigated. Based on the above, the bidirectional EL and the effect of ambient temperature (room temperature (RT) to 80 degrees C) on the luminescence properties of the diode have been investigated. The diode can be driven bidirectionally at very low currents (0.03 mA under forward and 0.01 mA under reverse) and produce high-brightness violet light at forward currents of 1-5 mA and reverse currents of 1-3 mA. Finally, the EL spectra were subjected to the Gaussian peak fitting process combined with energy band diagrams to analysis the luminescence mechanism of the diode. The EL spectra all show predominantly violet emission and interface defects emissions under different polarity current drive. The proposed bidirectional violet LED based on p-GaN/ n-InN heterojunction will be a potential commodity for the bidirectional driven LED market in the future.

Metal halide perovskite light-emitting diodes (PeLEDs) are excellent candidates in the field of lighting and display due to their outstanding optical-electrical properties. However, the solution-processed technology of perovskite films and the organic electron/hole transport layers of PeLEDs make it still challenging to improve the operational stability of devices. Herein, we successfully prepared highly luminescent CsPbBr3 perovskite films via vacuum-deposited method and then fabricated all-inorganic PeLEDs with the heterostructure of p-NiO/CsPbBr3/ n-Si. Our device exhibits pure-green emission with a wavelength of 527 nm, a narrow full width at half-maximum of 18 nm, and a maximum luminance of 51933 cd/m2, representing one of the best brightness pure-green PeLEDs. Most importantly, the PeLEDs exhibited great thermal stability with a heat resistance up to 80 degrees C. The electroluminescence peak position of the PeLEDs remains consistent when the ambient temperature increases from 40 degrees C to 110 degrees C. Moreover, the all-inorganic PeLEDs can maintain their good luminescence performance after seven thermal cycling tests (30 degrees C-100 degrees C). This work not only demonstrated a facile strategy to prepare high-quality pure-green CsPbBr3 perovskite films, but also provided an important all-inorganic device structure for high thermal stability of PeLED.

Self-powered ultraviolet (UV) photodetectors play an important role in environmental monitoring, aerospace and other fields because of the advantage of effective light response without an external power supply. Herein, a p-CuI/n-GaN heterojunction UV photodetector with self-powered function is constructed by vacuum thermal evaporation method. At 365 nm UV irradiation, the photodetector has an on/off ratio of 7536, a large photo-current (similar to 35 mA) and a fast response time (rise/decay time of 10.46/10.35 ms) at zero bias. There was no significant decrease in photocurrent during the 100 on/off cycles of the continuous test, and the photocurrent of the photodetector can maintain 93.17% of the initial value after continuous operation for 15 h without bias voltage. The rise in ambient temperature exhibits a negative effect on the UV photodetector, but when it is naturally cooled from 80 degrees C to room temperature (RT), the photocurrent can restore to 95% of the original level. Furthermore, the photodetector maintains superior stability even after being stored in air for 3 months of without package. This work not only proves the controllable preparation strategy of CuI thin films, but also provides an efficient structure for self-powered UV photodetectors with high operational and storage stability.

Owing to its exceptional optical and electrical properties, NiO had gained considerable attention in the past few years. A broad spectrum of its applications was expected, particularly in light-emitting diodes (LEDs). NiO thin films were concocted using radio frequency (RF) magnetron sputtering, then this study systematically investigated the correlation between substrate temperature and the film properties. Exceptional NiO thin films with excellent characteristics were successfully obtained. Moreover, leveraging the optimized substrate temperature, we fabricated ap-NiO/i-NiO/n-GaN LED. With this configuration, p-NiO served as the hole transport layer, while i-NiO, obtained through rapid annealing, functioned as the electron barrier layer (EBL), thus avoiding the lattice mismatch between the hole transport layer and the EBL. It demonstrated pronounced diode rectification characteristics, manifesting an impressively low leakage current of 3.76 x 10-12 A. Furthermore, it achieved ul-traviolet electroluminescence with a wavelength (-375 nm) and a narrow FWHM (-5 nm). Analysis revealed that the ultraviolet light emission in the diode predominantly originated from GaN-based near-band edge (NBE) luminescence.

In this work, beta-Ga2O3 thin films were deposited by radio frequency (RF) magnetron sputtering technique. The effect of oxygen-argon flow ratio (OAFR) on the formation of Frenkel defect pairs was systematically analyzed. The Frenkel defect pairs would become abundant when the OAFR was 25:25 sccm, resulting in a severe damage in crystalline quality and an increase in the density of disorder. With the further increase of OAFR, Frenkel defect pairs would dramatically decrease or even vanish due to the significant reduction of oxygen vacancies (V0). Immediately after that, on the basis of avoiding the influence of Frenkel defect pairs inside the beta-Ga2O3 films to the devices, the p-NiO/i-Ga2O3/n-GaN diode was fabricated from the as-prepared high-quality beta-Ga2O3 film after post-deposition annealing as the electron-blocking layer. Subsequently, its electrical characteristics were investigated in detail which exhibited excellent rectification characteristics under all test temperatures. Correspondingly, the device achieved electroluminescence (EL) with a dominant sharp emission peak in the ultraviolet range (similar to 375 nm). In the end, the energy band diagram was used for in-depth analysis of the EL mechanism.

The low lattice mismatch between β-Ga 2 O 3 and GaN alleviates interface defects and improves device performance, and the EL spectra of Ga 2 O 3 /GaN heterojunction devices emit ultra-violet and yellow-green light at forward and reverse bias.