Affiliation
NIMS
Title
Hexagonal Boron Nitride single crystals and thier impurity control
Abstract
Hexagonal boron nitride BN (hBN) and cubic BN (cBN) are known as the representative crystal structures of BN. The former is chemically and thermally stable, and has been widely used as an electrical insulator and heat-resistant materials. The latter, which is a high-density phase, is a super-hard material second only to diamond.
Some progresses in the synthesis of high purity boron nitride (BN) crystals were achieved by using Ba-BN as a growth solvent material at high pressure (HP) of 5.5GPa. Band-edge natures (cBN Eg=6.2eV and hBN Eg=6.4eV) were characterized by their optical properties. The key issue to obtain high purity crystals is to reduce oxygen and carbon contamination in the HP growth circumstances. Then an attractive potential of hBN as a deep ultraviolet (DUV) light emitter and also superior properties as substrate of graphene devices were realized.
Also, controlling of boron and nitrogen isotope ratio (10B, 11B and 15N) in hBN and cBN crystals can be now carried out by metathesis reaction under HPHT.
In this paper, recent studies on residual impurity control for BN single crystals obtained at high pressure with respect to impurity / isotope controls and their functionalization will be reported.