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This review describes the development history of group-III nitride light-emitting diodes (LEDs) for over 30 years, which has achieved brilliant achievements and changed people′s lifestyles. The development process of group-III nitride LEDs is the sum of challenges and solutions constantly encountered with shrinking size. Therefore, this paper uses these challenges and solutions as clues for review. It begins with reviewing the development of group-III nitride materials and substrates. On this basis, some key technological breakthroughs in the development of group-III nitride LEDs are reviewed, mainly including substrate pretreatment and p-type doping in material growth, the proposal of new device structures such as nano-LED and quantum dot (QD) LED, and the improvement in luminous efficiency, from the initial challenge of high-efficiency blue luminescence to current challenge of high-efficiency ultraviolet (UV) and red luminescence. Then, the development of micro-LEDs based on group-III nitride LEDs is reviewed in detail. As a new type of display device, micro-LED has drawn a great deal of attention and has become a research hotspot in the current international display area. Finally, based on micro-LEDs, the development trend of nano-LEDs is proposed, which is greener and energy-saving and is expected to become a new star in the future display field. [ABSTRACT FROM AUTHOR]

An AlGaN-based solar-blind UV heterojunction bipolar phototransistor (HBPT) with an AlGaN-based multiple quantum well (MQW) layer as the light absorption layer is proposed in this paper. On the basis of the individually optimized growth of the MQW light absorption layer and the p-type AlGaN base layer, the material growth, device preparation, and performance evaluation of the solar-blind UV HBPT are investigated in detail. The evaluations show that the fabricated two-end NPN-type phototransistor with a floating base presents a low dark current density of about 4.8 × 10−8 A cm−2 and a high peak responsivity of 4.55 A W−1 at 267 nm as the device is biased at a VCE of 12 V, corresponding to a high EQE of 2.1 × 103%. It also exhibits a quick transient response speed of 13.47 ns at a lower bias voltage (VCE = 3 V). These results favorably prove the feasibility of realizing a high performance solar-blind UV photodetector based on the AlGaN-based MQW HBPT. [ABSTRACT FROM AUTHOR]