Controlled growth of hexagonal GaN pyramids by hot-wall MOCVD

• Published in: Journal of crystal growth 2013-01, Vol.363, p.287-293
• Main Authors: Lundskog, Anders, Hsu, C.W., Nilsson, D., Karlsson, K.F., Forsberg, U., Holtz, P.O., Janzén, E.
• Format: Article
• Language: English
• Subjects: A3. Hot wall epitaxy A3. Metalorganic vapor phase epitaxy A3. Selective epitaxy B1. Nitrides; A3. Hot-wall epitaxy; A3. Metal−organic vapor phase epitaxy; A3. Selective epitaxy; Adsorption; Arrays; B1. Nitrides; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Evolution; Exact sciences and technology; Gallium nitrides; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Methods of nanofabrication; Physics; Pyramids; Surface chemistry; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Threading dislocations
• ISSN: 0022-0248; 1873-5002; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.11.014

Hexagonal GaN pyramids have been fabricated by hot-wall metal organic chemical vapor deposition (hot-wall MOCVD) and the growth evolution has been studied. It was concluded that the pyramid growth can be divided into two regimes separated by the adsorption kinetics of the {11¯01} surfaces of the pyramids. In the adsorption regime, the pyramids grow simultaneously in the and [0001] directions. In the zero-adsorption regime the pyramids grow only in the [0001] direction. Thus the pyramid growth ceases when the (0001) facet growth has been terminated. Large arrays consisting of highly uniform pyramids with apex radii of 3nm or less were achieved in the zero-adsorption regime. The growth-regime type was concluded to have a large impact on the uniformity degradation of the pyramids, and their optical properties. The impacts of threading dislocations which enter the pyramid from underneath are also discussed. ► Growth evolution of selective area grown hexagonal GaN pyramids reported. ► Adsorption/desorption kinetics on the {11¯01} facets on pyramids have major impact on the resulting non-uniformity of the hexagonal pyramids. ► Pyramids with nm-sized apices were achieved when the adatom adsorption/desorption on the {11¯01} facets cancels. ► Mechanism of uniformity degradation discussed. ► Optical characterization results of hexagonal pyramids reported and discussed.