Rectification Properties of Boron Nitride/Silicon Heterostructure Diodes

Abstract

Boron nitride is formed in three main crystalline forms: cubic, wurtzite, and hexagonal. Cubic boron nitride (cBN) is potentially expected as the semiconductor for high temperature condition due to the large band gap, high breakdown field, and high resistance to oxidation. Vapor deposition of cBN films on a foreign substrate is generally followed by an sp2-bonded BN (sp2BN) interlayer. The resistivity of sp2BN phase is usually higher than cBN phase by more than two orders of magnitude. However, the role of the sp2BN interlayer in rectification of cBN-based heterostructure diodes has not been clarified yet. In this study, rectification properties of p-type cBN/sp2BN/n-type Si heterostructure diodes fabricated under low-energy ion impact by plasma-enhanced chemical vapor deposition are studied in terms of the sp2BN interlayer [1]. A two-step biasing technique is developed to control the fraction of cBN phase and, hence, the thickness of the sp2BN interlayer in the films. We show that the rectification ratio at room temperature is increased up to the order of 104 at ±10 V of biasing with increasing the sp2BN thickness up to around 130 nm due to suppression of the reverse leakage current. The variation of the ideality factor in the low bias region is related to the interface disorders and defects, not to the sp2BN thickness. The forward current follows the Frenkel-Poole emission model in the sp2BN interlayer at relatively high fields when the anomalous effect is assumed. The thermionic emission model is not well applied to both the forward and reverse currents. We conclude that the transport of the minority carriers for reverse current is strongly limited by the high bulk resistance of the thick sp2BN interlayer, while that of the major carriers for forward current is much less affected. [1] K. Teii, H. Ito, N. Katayama, S. Matsumoto, J. Appl. Phys. 117 (2015) 055710.