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Localized epitaxy of gallium nitride (GaN) on silicon (Si) wafers is an efficient way to relax elastically the tensile stress generated in the GaN layer after growth, allowing epitaxy of thick layers for the fabrication of vertical power devices operating at high voltage. In this study, a 4.7 μm‐thick GaN layer is grown by metal–organic vapor phase epitaxy on 200 mm‐diameter Si wafers for the fabrication of quasi‐vertical Schottky and p‐n diodes. The uniformity of the doping concentration in the layer is mapped spatially by scanning spreading resistance microscopy, while scanning capacitance microscopy illustrates the differently doped regions in the p‐n diode. The net doping concentration is extracted by capacitance–voltage (C–V) measurements and it is found to be about 3 × 1016 cm−3. On a 140 μm‐diameter quasi‐vertical p‐n diode, destructive breakdown occurs at 402 V, with no periphery protection on the device, demonstrating that localized epitaxy of GaN on Si has great potential for vertical high‐power devices. [ABSTRACT FROM AUTHOR]

Mg‐doped AlGaN layers are needed for deep‐ultraviolet light emitting diodes (DUV‐LEDs). However because of the high activation energy of Mg in such layers, the ionization level of the Mg‐dopants is very low. In this paper a new design is proposed with a view to improve the wall plug efficiency (WPE) of DUV‐LEDs. The method consists in using a geometry combining a UV‐μLED and a gate covering the edges of the mesa. This approach is intended to by‐pass the problem of low ionization level of the dopants in p‐AlGaN. The simulated structures include a DUV‐LED mesa structure with Al0.5Ga0.5N/Al0.7Ga0.3N multiple quantum well (MQW) active region emitting around 265 nm. It also comprises a gate deposited on the sidewalls of the mesa. Simulations performed with Silvaco atlas will be presented. In particular we will show that by applying an appropriate voltage to the gate, holes can be efficiently injected into the active region. They reach the active region via an accumulation channel below the gate around the mesa, and then diffuse along the length of wells and easily recombine with electrons. Finally simulations show that the calculated WPE can be increased by a factor of 3 for an optimized structure geometry. [ABSTRACT FROM AUTHOR]