LAUSR

Carbon-doped GaN (GaN:C) Schottky diodes are prepared by controlling the destruction status of graphene interlayer (GI) on the substrate. The GI without a sputtered AlN capping layer (CL) was destroyed due to ammonia precursor etching behavior in a high-temperature epitaxy. The damaged GI, like nano-graphite as a solid-state carbon doping source, incorporated the epitaxial growth of GaN layer. The secondary ion mass spectroscopy depth profile indicated that the carbon content in GaN layer can be tuned further by optimizing the sputtering temperature of AlN CL due to the better capping ability of high crystalline quality AlN CL on GI being achieved at higher temperature. The edge-type threading dislocation density (TDD) and carbon concentration of the GaN:C layer with an embedded 550 °C-grown AlN CL on a GI substrate can be significantly reduced to 2.28x10^9 cm^-2 and ~2.88x10^18 cm^-3, respectively. Thus, a Ni-based Schottky diode with ideality factor of 1.5 and barrier height of 0.72 eV was realized on GaN:C. The series resistance increased from 28 k-ohm at 303 K to 113 k-ohm at 473 K, while the positive temperature coefficient (PTC) of series resistance was ascribed to the carbon doping that induced the compensation effect and lattice scattering effect. The decrease of the donor concentration was confirmed by temperature-dependent capacitance-voltage (C-V-T) measurement. The PTC characteristic of GaN:C Schottky diodes created by dissociating the GI as a carbon doping source should allow for the future use of high-voltage Schottky diodes in parallel, especially in high temperature environments.