Due to the increased surface-to-volume ratio, the surface recombination caused by sidewall defects is a key obstacle that limits the external quantum efficiency (EQE) for GaN-based micro-light-emitting diodes (µLEDs). In this work, we propose selectively removing the periphery p+-GaN layer so that the an artificially formed resistive ITO/p-GaN junction can be formed at the mesa edge. Three types of LEDs with different device dimensions of 30 × 30 µm2, 60 × 60 µm2 and 100 × 100 µm2 are investigated, respectively. We find that such resistive ITO/p-GaN junction can effectively prevent the holes from reaching the sidewalls for µLEDs with smaller size. Furthermore, such confinement of injection current also facilitates the hole injection into the active region for µLEDs. Therefore, the surface-defect-caused nonradiative recombination in the edge of mesa can be suppressed. Meantime, a reduction of current leakage caused by the sidewall defects can also be obtained. As a result, the measured and calculated external quantum efficiency (EQE) and optical output power for the proposed LED with small sizes are increased.

It is known that light extraction efficiency (LEE) for AlGaN-based deep ultraviolet light-emitting didoes (DUV LEDs) can be enhanced by using truncated cone arrays with inclined sidewalls. In this work, the air-cavity-shaped inclined sidewall is applied and the p-GaN layer at the top of the truncated cone is laterally over-etched so that more light escape paths are generated for AlGaN-based DUV LEDs. The experimental results manifest that when compared with DUV LEDs only having the air-cavity-shaped inclined sidewall, the optical power for the DUV LEDs with laterally over-etched p-GaN at the top of the truncated cone is enhanced by 30% without sacrificing the forward bias. It is because the over-etched p-GaN makes little effect on the carrier injection and does not affect the ohmic contact resistance. Moreover, the simulation results show that the truncated cone with laterally over-etched p-GaN layer can enhance the LEE because the reduced p-GaN area can suppress the optical absorption and supplies additional light paths for DUV photos. Then, more light will be reflected into escape cones at the sapphire side.

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Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and the third most common cause of death from cancer, after lung and stomach cancer. Hepatitis B virus (HBV) infection is closely related to HCC and is a major cause of HCC. HBV is a lysogenic virus of the hepadnavirus family. Its genome presents a slack, ring-like, double-chain structure, containing four open reading frames. The X region encodes the product HBV X protein (HBx), which is a multifunctional regulatory protein that plays an important role in intracellular signal transduction, viral genome replication and transcription, cell proliferation and apoptosis, cell cycle progression, protein degradation, and genetic stability of hepatocytes. This article summarizes the recent research on the mechanism of promotion of initiation and progression of HCC by HBx protein.

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