In this letter, we report on demonstrating high-performance lateral GaN Schottky barrier diode (SBD) on silicon substrate with low turn-on voltage ( $\text{V}_{\mathbf {on}}$ ), high breakdown voltage (BV) with low reverse leakage current ( $\text{I}_{\mathbf {R}}$ ), and high power figure of merit (P-FOM) through anode engineering technique. Lateral GaN SBD with anode-cathode distance ( $\text{L}_{\mathbf {AC}}$ ) of $25~\mu \text{m}$ demonstrates a $\text{V}_{\mathbf {on}} =0.38$ V, a BV of >3 kV at a $\text{I}_{\mathbf {R}}$ of $10\mu \text{A}$ /mm and differential specific ON-resistance ( $\text{R}_{\mathbf {on,sp}}$ ) of 2.94 $\text{m}\Omega ~\cdot $ cm ² , yielding a high P-FOM of more than 3 GW/cm ² . To the best of our knowledge, this P-FOM is the highest value among all the GaN SBDs on any substrates. Combining with 5 A forward current ( $\text{I}_{\mathbf {F}}$ ) and reverse BV >2 kV of a large periphery device with perimeter of 20 mm, GaN SBD with anode engineering technique shows its great promise for next generation power electronics.

N-polar AlₓGa₁₋ₓN-based 365-nm ultraviolet (UV) light-emitting diodes (LEDs) with a hole-supplier layer composed of p-type Al0.2Ga0.8N/GaN superlattice (SL) doping or bulk doping structures are numerically investigated over Ga-polar UV-LEDs counterpart. The simulation results demonstrate that N-polar LEDs are favorable in mitigating the negative effect of the polarization-induced electric field. Thus, it exhibits superiority in promoting carriers confinement capability and suppressing electrons overflow over Ga-polar. As a result, the internal quantum efficiency, light output power, and electroluminescence intensity are significantly improved. In addition, both Ga-polar and N-polar devices exhibit the increased hole concentrations and higher radiative recombination rate within quantum wells after adopting SL p-doping structure. From the simulated energy band diagrams, the polarization-induced higher acceptor ionization rates at the heterostructure interfaces are observed. Evidently, the UV-LEDs based on N-polar SL p-doping structure are very effective to improve its performance, which is promising in achieving high-performance UV-LEDs of the future fabrication.

GaN was grown on the sputtered AlN/patterned sapphire substrate under two growth modes by metal-organic chemical vapor deposition, which was named as ``rising tide'' and ``tsunami'' growth modes, respectively, due to different characteristics of the GaN growth process. High-quality GaN epilayer was obtained under ``tsunami'' growth mode, and the full-width at half-maximums of GaN (002)/(102) high-resolution X-ray diffraction rocking curves were 58/90 arcsec. The green InGaN/GaN light-emitting diodes fabricated on GaN under ``tsunami'' growth mode exhibited both higher light output power and external quantum efficiency. By monitoring the GaN films at different growth stages using the scanning electron microscope and the transmission electron microscope as well as cathodoluminescence, the dislocation annihilation mechanisms were researched. Under ``tsunami'' growth mode, GaN grew into the shape of a truncated pyramid that promoted dislocations originated from flat area bend toward the inclined planes, and it was noteworthy that the propagation of dislocations in grains on the conical surface was inhibited. While under ``rising tide'' growth mode, the dislocations on the conical surface had chances to extend.

In this paper, we carried out a comprehensive study and optimization of implementing p-NiO in the β-Ga₂O₃ based diodes, including Schottky barrier diode (SBD) with p-NiO guard ring (GR), p-NiO/β-Ga₂O₃ heterojunction (HJ) barrier Schottky (HJBS) diode, and HJ-PN diode through the TCAD simulation. In particular, we provide design guidelines for future p-NiO-related Ga₂O₃ diodes with material doping concentrations and dimensions to be taken into account. Although HJ-PN has a ~1 V higher turn-on voltage (V_on), its breakdown voltage (BV) is the highest among all diodes. We found that for SBD with p-NiO GRs and HJBS, their forward electrical characteristics and reverse leakage current are related to the total width and the doping concentration of p-NiO, the BV is only related to the doping concentration of p-NiO_, and the optimal doping concentration of p-NiO is found to be 4 × 10¹⁷ cm⁻³. Compared with the SBD without p-NiO, the BV of the SBD with p-NiO and HJBS diode can be essentially improved by 3 times. As a result, HJ-PN diode, SBD with p-NiO GRs, and HJ-BS diode achieve a BV/specific on-resistance (R_on,sp) of 5705 V/4.3 mΩ·cm², 3006 V/3.07 mΩ·cm², and 3004 V/3.06 mΩ·cm², respectively. Based on different application requirements, this work provides a useful insight about the diode selection with various structures.

Defect behaviors in the degradation of AlGaN-based UV-C light emitting diodes (LEDs) under constant current stress have been intensively investigated in this work. It is found that both the reduction of the optical power and the increase in the leakage current are derived from the newly generated Ga vacancy (V_Ga) along dislocation, based on the evidence of a strong “yellow” emission peak at 515 nm in the photoluminescence spectra and an energy level of 0.25–0.38 eV. More importantly, the defect evolution behind it was determined through the deep level transient spectroscopy, secondary ion mass spectrometry measurements, and density functional theory. V_Ga is found to be generated by the departure of the unintentionally doped Mg from Mg_Ga along dislocation in the Si-doped region. The high activity of the unintentionally doped Mg under electrical stress can be an essential factor in the degradation of UV-C LEDs. This study not only provides an in-depth insight into the electrical stress-induced degradation in UV-C LEDs but also sheds light on the way for fabricating AlGaN-based devices with high reliability.