Fabrication of GaN/Diamond Heterointerface and Interfacial Chemical Bonding State for Highly Efficient Device Design

Jianbo Liang, Ayaka Kobayashi, Yasuo Shimizu, Yutaka Ohno, Seong Woo Kim, Koji Koyama, Makoto Kasu, Yasuyoshi Nagai, Naoteru Shigekawa

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


The direct integration of gallium nitride (GaN) and diamond holds much promise for high-power devices. However, it is a big challenge to grow GaN on diamond due to the large lattice and thermal-expansion coefficient mismatch between GaN and diamond. In this work, the fabrication of a GaN/diamond heterointerface is successfully achieved by a surface activated bonding (SAB) method at room temperature. A small compressive stress exists in the GaN/diamond heterointerface, which is significantly smaller than that of the GaN-on-diamond structure with a transition layer formed by crystal growth. A 5.3 nm-thick intermediate layer composed of amorphous carbon and diamond is formed at the as-bonded heterointerface. Ga and N atoms are distributed in the intermediate layer by diffusion during the bonding process. Both the thickness and the sp2-bonded carbon ratio of the intermediate layer decrease as the annealing temperature increases, which indicates that the amorphous carbon is directly converted into diamond after annealing. The diamond of the intermediate layer acts as a seed crystal. After annealing at 1000 °C, the thickness of the intermediate layer is decreased to approximately 1.5 nm, where lattice fringes of the diamond (220) plane are observed.

Original languageEnglish
Article number2104564
JournalAdvanced Materials
Issue number43
Publication statusPublished - 2021 Oct 28


  • GaN/diamond heterointerfaces
  • intensity gradients
  • residual stress
  • sp ratio
  • surface-activated bonding


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