Conformal Growth of Hexagonal Boron Nitride on High-Aspect-Ratio Silicon-Based Nanotrenches

We successfully accomplished the conformal growth of sp2- hybridized few-layer h-BN over an array of Si-based nanotrenches with a 45 nm pitch and an aspect ratio of similar to 7:1 by using the pulsed-mode metal- organic chemical vapor deposition (MOCVD) method. Surface-sensitive X-ray absorption fine structure spectroscopy and density functional theory calculations revealed that the B-O bonds formed on the noncatalytic SiO2 surface act as nucleation sites for the subsequential formation of mixed sp2- and sp3-hybridized BON2 and BN3 at the very initial stage of the pulsed-mode injection of MOCVD precursors, enabling the conformal growth of few-layer sp2-hybridized h-BN with an excellent step coverage. We believe that these results can provide a broad avenue for the implementation of fascinating two-dimensional layered materials for current state-of-the-art three-dimensional Si-based nanoscale architectures, overcoming the downscaling limits.