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

Wen Cheng Ke, Solomun Teklahymanot Tesfay, Tae Yeon Seong, Zhong Yi Liang, Chih Yung Chiang, Chieh Yi Chen, Widi Son, Kuo Jen Chang, Jia Ching Lin

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4 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)48086-48094
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number51
Publication statusPublished - 2019 Dec 26


  • AlN capping
  • carbon-doped GaN
  • graphene
  • schottky diode
  • threading dislocation

ASJC Scopus subject areas

  • Materials Science(all)


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