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We report high-performance homojunction GaN avalanche photodiodes (APDs) grown on a low-defect GaN substrate and fabricated with an ion-implantation isolation method. High-quality p-i-n GaN layers were grown using metalorganic chemical vapor deposition (MOCVD), and an effective device isolation method using optimized nitrogen ion implantation was developed to provide significant leakage current suppression on the etched mesa sidewalls. Fabricated GaN APDs showed an ultralow dark current density 106 at a reverse bias of 71.5 V under deep-ultraviolet (DUV) illumination at $\lambda =280$ nm. A further temperature-dependent study of the dark current indicated that a trap-assisted tunneling process predominates the leakage current component that also contributes to the carrier multiplication process near the avalanching breakdown.

We determined the optical and electrical characteristics of GaN-based, ultraviolet micro light emitting diodes (microLEDs). Such microLEDs are essential to next-generation high-resolution micro-displays. Square-shaped microLEDs of different sizes (side lengths: 5-50 μm) were designed. The peak emission wavelength of these devices shifted