Characteristics of aluminum nitride films on hexagonal boron nitride buffer layers using various growth methods through metal organic chemical vapor deposition

Abstract

Hexagonal boron nitride (hBN) combined with III-nitride materials is attracting increasing attention for widening the applications of III-nitride materials. Three methods were used to grow the hBN buffer layer: (i) 2-step (low and high temperature), (ii) 1-step (high temperature), and (iii) pre-TEB surface treatment method. The optical properties of the hBN buffer layers were determined through Raman spectroscopy and absorbance measurements to characterize the combination between the III-nitride material (AlN) and hBN. The crystal quality of the AlN film grown under the same conditions on three hBN buffer layers has investigated by X-ray diffraction (XRD). XRD data established that the surface roughness of the hBN layer and density of the AlN nuclei are important factors for crystal quality of III-nitride material. The surface roughness of the hBN layers varied for the different growth methods, while the V/III ratio for each method remained unchanged. This difference in the surface roughness was confirmed to be related to the bonding configuration within the hBN layer, and was further confirmed by X-ray photoelectron spectroscopy to be due to the strong interactions between BN with the substrate (B1). In addition, the strongly interacting BN bond, which is dependent on the method used for the growth of the buffer layer, resulted in a peel-off of the AlN layer. This phenomenon did not occur at the hBN/sapphire interface, but occurred at the AlN/hBN interface, confirming that the strong interaction bonding between BN and the substrate weakens adhesion at the AlN/hBN interface.