Atomic-Layer Deposition of Single-Crystalline BeO Epitaxially Grown on GaN Substrates

Seung Min Lee, Jung Hwan Yum, Seonno Yoon, Eric S. Larsen, Woo Chul Lee, Seong Keun Kim, Shahab Shervin, Weijie Wang, Jae Hyun Ryou, Christopher W. Bielawski, Jungwoo Oh

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Abstract

We have grown a single-crystal beryllium oxide (BeO) thin film on a gallium nitride (GaN) substrate by atomic-layer deposition (ALD) for the first time. BeO has a higher thermal conductivity, bandgap energy, and dielectric constant than SiO2. As an electrical insulator, diamond is the only material on earth whose thermal conductivity exceeds that of BeO. Despite these advantages, there is no chemical-vapor-deposition technique for BeO-thin-film deposition, and thus, it is not used in nanoscale-semiconductor-device processing. In this study, the BeO thin films grown on a GaN substrate with a single crystal showed excellent interface and thermal stability. Transmission electron microscopy showed clear diffraction patterns, and the Raman shifts associated with soft phonon modes verified the high thermal conductivity. The X-ray scan confirmed the out-of-plane single-crystal growth direction and the in-plane, 6-fold, symmetrical wurtzite structure. Single-crystalline BeO was grown on GaN despite the large lattice mismatch, which suggested a model that accommodated the strain of hexagonal-on-hexagonal epitaxy with 5/6 and 6/7 domain matching. BeO has a good dielectric constant and good thermal conductivity, bandgap energy, and single-crystal characteristics, so it is suitable for the gate dielectric of power semiconductor devices. The capacitance-voltage (C-V) results of BeO on a GaN-metal-oxide semiconductor exhibited low frequency dispersion, hysteresis, and interface-defect density.

Original languageEnglish
Pages (from-to)41973-41979
Number of pages7
JournalACS Applied Materials and Interfaces
Volume9
Issue number48
DOIs
Publication statusPublished - 2017 Dec 6

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Cite this

Lee, S. M., Yum, J. H., Yoon, S., Larsen, E. S., Lee, W. C., Kim, S. K., Shervin, S., Wang, W., Ryou, J. H., Bielawski, C. W., & Oh, J. (2017). Atomic-Layer Deposition of Single-Crystalline BeO Epitaxially Grown on GaN Substrates. ACS Applied Materials and Interfaces, 9(48), 41973-41979. https://doi.org/10.1021/acsami.7b13487