Anisotropic Dielectric Breakdown Strength of Single Crystal Hexagonal Boron Nitride.
Dielectric breakdown has historically been of great interest from the perspectives of fundamental physics and electrical reliability. However, to date, the anisotropy in the dielectric breakdown has not been discussed. Here, we report an anisotropic dielectric breakdown strength (EBD) for h-BN, which is used as an ideal substrate for two-dimensional (2D) material devices. Under a well-controlled relative humidity, EBDvalues in the directions both normal and parallel to the c axis (EBD⊥cand EBD∥c) were measured to be 3 and 12 MV/cm, respectively. When the crystal structure is changed from sp3of cubic-BN (c-BN) to sp2of h-BN, EBD⊥cfor h-BN becomes smaller than that for c-BN, while EBD∥cfor h-BN drastically increases. Therefore, h-BN can possess a relatively high EBDconcentrated only in the direction parallel to the c axis by conceding a weak bonding direction in the highly anisotropic crystal structure. This explains why the EBD∥cfor h-BN is higher than that for diamond. Moreover, the presented EBDvalue obtained from the high quality bulk h-BN crystal can be regarded as the standard for qualifying the crystallinity of h-BN layers grown via chemical vapor deposition for future electronic applications.
Department of Materials Engineering, The University of Tokyo , Tokyo 113-8656, Japan.
Yoshiaki
Y
Hattori
National Institute of Materials Science , Ibaraki 305-0044, Japan.
Takashi
T
Taniguchi
National Institute of Materials Science , Ibaraki 305-0044, Japan.
Kenji
K
Watanabe
Department of Materials Engineering, The University of Tokyo , Tokyo 113-8656, Japan.|PRESTO, Japan Science and Technology Agency (JST) , Tokyo 113-8656, Japan.
Kosuke
K
Nagashio
adsorbed water; anisotropy; cathodoluminescence spectroscopy; dielectric breakdown; hexagonal boron nitride; layered structure