Influence of Sapphire Substrate Orientation on the van der Waals Epitaxy of III-Nitrides on 2D Hexagonal Boron Nitride: Implication for Optoelectronic Devices
Résumé
Van der Waals (vdW) epitaxy of three-dimensional (3D) device structures on two-dimensional (2D) layers is particularly interesting for III-nitrides because it may relax lattice matching and thermal mismatch requirements and can permit convenient lift-off of epilayers and opto-electronic devices. In this article, we report vdW epitaxy of 3D GaN/AlGaN on 2D h-BN grown on a-, c-, and m-plane sapphire substrates via metal-organic chemical vapor phase epitaxy. First, we study 2D h-BN layers grown on a-, c-, and m-plane sapphire to demonstrate the substrate effect on h-BN growth and h-BN alignment. We find that h-BN can align itself to its preferred c-axis with a slight misorientation on m-plane sapphire substrate. However, the difference in crystallographic orientation, thermal expansion coefficient, and surface energy of differently oriented sapphire substrates strongly influence the surface morphology (good for a-and c-plane) and the adhesion of h-BN layers (lift-off only possible for c-plane). Second, vdW growth of 3D GaN/AlGaN on 2D h-BN grown on a-, c-, and m-planes of sapphire was investigated. HR-XRD 2θ-ω scan and selected area electron diffraction pattern was used to demonstrate the misorientation of GaN/AlGaN grown on 2D h-BN/m-plane sapphire compared to polar GaN grown on 2D h-BN/aand c-plane sapphire. It was found that the morphology and crystalline quality of GaN/AlGaN is directly affected by the 2D h-BN layers. These results provide initial insight into the impact of substrate orientation, thereby acting as a guide for potential design of III-nitride/h-BN vdW epitaxy seeking to use non-polar or semi-polar planes of sapphire for opto-electronic devices such as LEDs, high power electronics and detectors.
Mots clés
van der Waals epitaxy Metal-organic chemical vapor phase epitaxy (MOVPE) twodimensional materials hexagonal Boron Nitride III-nitrides substrate orientations
van der Waals epitaxy
Metal-organic chemical vapor phase epitaxy (MOVPE)
twodimensional materials
hexagonal Boron Nitride
III-nitrides
substrate orientations
Domaines
Sciences de l'ingénieur [physics]
Fichier principal
Influence of Sapphire Substrate Orientation on Van der Waals Epitaxy of III-Nitrides on 2D Hexagonal Boron Nitride.pdf (1.37 Mo)
Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)