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Electric breakdown in GaN p-n junctions was investigated. GaN p+-p-n+ structures were grown on 6H–SiC substrates by metalorganic chemical vapor deposition. Mg and Si were used as dopants. Mesa structures were fabricated by reactive ion etching. Capacitance–voltage measurements showed that the p-n junctions were linearly graded. The impurity gradient in the p-n junctions ranged from 2×1022 to 2×1023 cm−4. Reverse current–voltage characteristics of the p-n junctions were studied in the temperature range from 200 to 600 K. The diodes exhibited abrupt breakdown at a reverse voltage of 40–150 V. The breakdown had a microplasmic nature. The strength of the electric breakdown field in the p-n junctions depended on the impurity gradient and was measured to be from 1.5 to 3 MV/cm. It was found that the breakdown voltage increases with temperature. The temperature coefficient of the breakdown voltage was ∼2×10−2 V/K.

Articles you may be interested inGaN epitaxial films grown by hydride vapor phase epitaxy on polycrystalline chemical vapor deposition diamond substrates using surface nanostructuring with TiN or anodic Al oxide Effect of sapphire-substrate thickness on the curvature of thick GaN films grown by hydride vapor phase epitaxy

We have studied epitaxial GaN layers grown by hydride vapour phase epitaxy (HVPE) on porous GaN sublayers formed on SiC substrates. It was shown that these layers can be grown with good surface morphology and high crystalline quality. X-ray, Raman and photoluminescent (PL) measurements showed that the stress in the layers grown on porous GaN was reduced to 0.1-0.2 GPa, while the stress in the layers grown directly on 6H-SiC substrates remains at its usual level of about 1 GPa. Thus, we have shown that growth on porous GaN sublayer is a promising method for fabrication of high quality epitaxial layers of GaN with low strain values.

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