Solid-State Carbon-Doped GaN Schottky Diodes by Controlling Dissociation of the Graphene Interlayer with a Sputtered AlN Capping Layer

Abstract

Carbon-doped GaN (GaN:C) Schottky diodes are prepared by controlling the destruction status of the graphene interlayer (GI) on the substrate. The GI without a sputtered AlN capping layer (CL) was destroyed because of ammonia precursor etching behavior in a high-temperature epitaxy. The damaged GI, like nanographite as a solid-state carbon doping source, incorporated the epitaxial growth of the GaN layer. The secondary ion mass spectroscopy depth profile indicated that the carbon content in the GaN layer can be tuned further by optimizing the sputtering temperature of AlN CL because of the better capping ability of high crystalline quality AlN CL on GI being achieved at higher temperature. The edge-type threading dislocation density 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 2.28 × 109 cm–2 and ∼2.88 × 1018 cm–3, respectively. Thus, a Ni-based Schottky diode with an ideality factor of 1.5 and a barrier height of 0.72 eV was realized on GaN:C. The series resistance increased from 28 kΩ at 303 K to 113 kΩ 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.

High-Quality Transferred GaN-Based Light-Emitting Diodes through Oxygen-Assisted Plasma Patterning of Graphene

“…Graphene, the most well-known 2D material, possesses a crystal structure with hexagonal arrangement, which is similar to the c -plane atoms of nitride. Therefore, graphene can serve as a removable layer for the epitaxy growth of III-N films, thereby laying a technical foundation for the realization of transferable and flexible LEDs. − Unfortunately, the lack of dangling bonds of the graphene surface greatly limits the effective nucleation of nitrides epitaxially thereon, , and the epitaxial mechanism of III-N grown on graphene is still ambiguous.…”