Transformation of c-oriented nanowall network to a flat morphology in GaN films on c-plane sapphire
- International Centre for Material Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States)
Highlights: {yields} High quality wurtzite structures GaN nanowall network formed on c-plane sapphire. {yields} Tapering of nanowalls at the apex cause electron confinement effects. {yields} Temperature dependent transformation of the six fold nanowall network to a flat morphology. {yields} Growth kinetics is influenced by adatom diffusion, interactions and bonding for GaN layer. -- Abstract: The work significantly optimizes growth parameters for nanostructured and flat GaN film in the 480-830 {sup o}C temperature range. The growth of ordered, high quality GaN nanowall hexagonal honeycomb like network on c-plane sapphire under nitrogen rich (N/Ga ratio of 100) conditions at temperatures below 700 {sup o}C is demonstrated. The walls are c-oriented wurtzite structures 200 nm wide at base and taper to 10 nm at apex, manifesting electron confinement effects to tune optoelectronic properties. For substrate temperatures above 700 {sup o}C the nanowalls thicken to a flat morphology with a dislocation density of 10{sup 10}/cm{sup 2}. The role of misfit dislocations in the GaN overlayer evolution is discussed in terms of growth kinetics being influenced by adatom diffusion, interactions and bonding at different temperatures. The GaN films are characterized by reflection high energy electron diffraction (RHEED), field emission scanning electron (FESEM), high resolution X-ray diffraction (HRXRD) and cathodoluminescence (CL).
- OSTI ID:
- 22210096
- Journal Information:
- Materials Research Bulletin, Vol. 46, Issue 11; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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