Hexagonal Boron Nitride Single Crystal Growth from Solution with a Temperature Gradient
Jiahan Li, Chao Yuan, Christine Elias, Junyong Wang, Xiaotian Zhang, Gaihua Ye, Chaoran Huang, Martin Kuball, Goki Eda, Joan M. Redwing, Rui He, Guillaume Cassabois, Bernard Gil, Pierre Valvin, Thomas Pelini, Bin Liu, James H. Edgar
Abstract
Hexagonal boron nitride (hBN) is attracting much attention due to its tremendous applications including nanophotonic and electronic devices, substrates for two-dimensional (2D) materials, heat management materials, etc. To achieve the best device performance, large area hBN single crystals are required. Herein, large-area (>500 μm each), high-quality (defect density < 0.52/μm2) bulk hBN single crystals are grown from molten metal solutions with a temperature gradient. The narrow Raman line widths of the intralayer E2g mode peak and the interlayer shear mode, the strong and sharp phonon-assisted transition photoluminescence peaks, and the high thermal conductivity demonstrate that the hBN produced by this method has a high crystal quality with a low density of defects. Atomic force microscope images show that atomically flat layers of hBN can be produced by exfoliation. This study not only demonstrates a new strategy for growing large hBN single crystals but also provides high quality thick and thin hBN layers for nanodevice applications.