In this note, we demonstrate direct high-temperature growth of single-crystalline GaN on c-plane ScAlMgO4 substrates by metalorganic chemical vapor deposition, without using low-temperature buffers. We found that a trimethylaluminium preflow was crucial to suppress island growth and to achieve uniform mirror-like Ga-polar GaN layers. The preflow time was found to have a direct impact on the crystalline quality of GaN. We also show that thin GaN layers directly grown at high temperature can be used as buffers for the growth of lattice-matched In0.17Ga0.83N layers on ScAlMgO4. The presented results demonstrate the potential of direct growth of GaN on ScAlMgO4.

We report the effects of high-energy (23 GeV) proton irradiation at large fluences on packaged high-power GaN-based white light-emitting diodes with YAG:Ce phosphors. From optical and electrical measurements, we assume that proton irradiation degrades only the GaN LED die up to fluences of at least 2 ' 10 14 p/cm 2 , and we demonstrate that it produces nonradiative recombination centres which increase the leakage current and diminish the carrier density in the quantum wells and hence the output optical power. We also propose for the first time a model correlating optical and electrical degradation induced by radiation.

We demonstrate quasi-vertical reverse blocking (RB) MOSFETs on 6.7 μm thick GaN grown on a 6 inch Si substrate by metalorganic chemical vapor deposition. The RB capability was achieved by replacing the ohmic drain with a quasi-vertical Schottky drain, resulting in a RB voltage of ∼300 V while preserving the ON-resistance (R on,sp). Schottky contacts on etched i-GaN surface were realized through an optimized fabrication process based on tetramethylammonium hydroxide treatments. The fabricated RB-MOSFET had a low R on,sp of 4.75 mΩ cm2, current density of ∼0.9 kA cm−2 and a forward blocking voltage of 570 V.

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