Epitaxial growth of cubic boron nitride (c-BN)

Abstract

  Boron nitride (BN) has several polymorphs with different bonding states and crystal structures. Among them, sp³-bonded cubic boron nitride (c-BN) is a promising ultrawide-bandgap semiconductor for high-power electron device applications due to its large bandgap energy of 6.25 eV and high breakdown field of ~17.5 MV/cm. However, the epitaxial growth of c-BN has been challenging because it is a metastable phase. Recently, we have successfully achieved the epitaxial growth of c-BN layers on diamond substrates by developing an ion-beam-assisted MBE with independent boron, nitrogen radical and Ar⁺ ion sources. In this article, we first introduce the physical properties of c-BN, then describe our ion-beam-assisted MBE technology for phase-pure c-BN epitaxial growth and discuss the growth mechanism based on the established growth phase diagram. Finally, we present n-type conductivity control of c-BN with in-situ Si doping and discuss the carrier scattering mechanisms.