A method of combining the AlGaN/GaN superlattices and Mg delta doping was proposed to achieve a high conductivity p-type GaN layer. The experimental results provided the evidence that the novel doping technique achieves superior p-conductivity. The Hall-effect measurement indicated that the hole concentration was increased by 2.06 times while the sheet resistivity was reduced by 48%. The fabricated green-yellow light-emitting diodes using the achieved high conductivity p-type GaN layer showed an 8- and 10-times enhancement of light output power and external quantum efficiency, respectively. The subsequent numerical calculation was conducted by using an Advanced Physical Model of Semiconductor Device to reveal the mechanism of enhanced device performance. This new doping technique offers an attractive solution to the p-type doping problems in wide-bandgap GaN or AlGaN materials.

Due to the excellent quantum conversion and spectral response characteristics of the AlGaN photocathode, it has become the most promising III-V group semiconductor photocathode in solar-blind signal photoconversion devices in the ultraviolet band. Herein, the influence factors of the time-resolved characteristics of the AlGaN photocathode are researched by solving the photoelectron continuity equation and photoelectron flow density equation, such as the AlN/AlGaN interface recombination rate, AlGaN electron diffusion coefficient, and AlGaN activation layer thickness. The results show that the response time of the AlGaN photocathode decreases gradually with the increase in AlGaN photoelectron diffusion coefficient and AlN/AlGaN interface recombination rate, but the response time of the AlGaN photocathode gradually becomes saturated with the further increase in AlN/AlGaN interface recombination rate. When the thickness of the AlGaN photocathode is reduced from 250 nm to 50 nm, the response time of the AlGaN photocathode decreases from 63.28 ps to 9.91 ps, and the response time of AlGaN photocathode greatly improves. This study provides theoretical guidance for the development of a fast response UV detector.

A method to improve the performance of ultraviolet light-emitting diodes (UV-LEDs) with stair-like Si-doping GaN layer is investigated. The high-resolution X-ray diffraction shows that the UV-LED with stair-like Si-doping GaN layer possesses better quality and a lower dislocation density. In addition, the experimental results demonstrate that light output power and wall plug efficiency of UV-LED with stair-like Si-doping GaN are significantly improved. Through the analysis of the experimental and simulation results, we can infer that there are two reasons for the improvement of photoelectric characteristics: reduction of dislocation density and alleviating of current crowding of UV-LEDs by introduced stair-like Si-doping GaN.

InGaAs photocathodes operating in the 0.9–1.7 μm spectral band are fundamentally limited by optical reflection losses and incomplete light absorption in thin active layers. In this work, we constructed periodic micro-nanostructured InGaAs photocathode models using finite-difference time-domain (FDTD) simulations, and systematically compared five micro-nanostructures (square pillars, circular pillars, square truncated pyramids, hexagonal prisms, and square pyramids) against a planar reference structure. At a wavelength of 1.55 μm, coupled scans of lateral dimension and height yielded maximum absorptance values of 0.749 for square pillars (0.6 μm side length, 0.9 μm height) and 0.682 for circular pillars (0.9 μm diameter, 0.9 μm height), corresponding to enhancements of 35.4% and 23.3%, respectively, relative to the planar reference. Circular pillars exhibited the lowest reflectance (0.072); however, their higher forward transmittance caused lower overall absorptance than that of square pillars. We then coupled the FDTD generation profiles to a steady-state drift-diffusion analysis of carrier collection. Under normalized illumination and a 5 V bias, the integrated generation increased by 29.2%. The modeled internal generation-rate-weighted collection efficiency η_C increased from 0.499 to 0.680, corresponding to a 36.2% enhancement, and the internally collected carrier-rate proxy increased by 76.1% relative to the planar reference. Under ideal fully-passivated side-wall conditions, the internally collected carrier-rate proxy increased by 76.1% relative to the planar reference. This study provides theoretical guidance for designing and optimizing high-performance micro/nanostructured InGaAs photocathodes.