Interfacial properties of self-assembled GaN nanowires on pre-processed Al2O3(0001) surfaces
| Autor: | Holm Kirmse, Martin Eickhoff, T. Koukoula, Joseph Kioseoglou, Florian Furtmayr, Th. Kehagias, Ph. Komninou, Th. Karakostas |
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| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Materials science Nanostructure business.industry Mechanical Engineering Nucleation Nanowire Nanotechnology 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Amorphous solid Crystal Mechanics of Materials Transmission electron microscopy 0103 physical sciences Optoelectronics General Materials Science Vapor–liquid–solid method 0210 nano-technology business Molecular beam epitaxy |
| Zdroj: | Materials Science in Semiconductor Processing. 55:46-50 |
| ISSN: | 1369-8001 |
| DOI: | 10.1016/j.mssp.2016.03.015 |
| Popis: | Surface treatment of the foreign substrate is a critical factor influencing heteroepitaxial catalyst-free growth of nanowires, their crystal quality, their diameter and their areal density. To this end, catalyst-free growth of GaN nanowires on Al2O3(0001) by plasma-assisted molecular beam epitaxy was achieved using the following substrate surface treatments: (a) deposition of a SixNy layer on nitridated Al2O3 surface, and (b) deposition of Si on bare Al2O3 surface. The nanostructure of GaN nanowires and GaN/Al2O3 interfaces was explored by quantitative high-resolution transmission electron microscopy and related analytical methods. Spontaneous growth of GaN nanowires was realized on the amorphous SixNy layer, while a discontinuous crystalline zone in contact with Al2O3 was identified as partially strained AlN. Subsequently, GaN nanowires were directly grown on top of Al2O3 among stress-free Si islands. The orientation relation of these islands with the substrate was the [112]( 1 ¯ 1 ¯ 1 )Si//[ 1 1 ¯ 00 ](0001)Al2O3, providing the minimum lattice misfit between the two structures. Increasing the Si deposition time a higher density of Si islands was realized, leading to non-coalesced nanowires of lower density and better structural quality. Hence, the presence of Si islands induced a mask-like effect on the nucleation of GaN nanowires that can be exploited for a controlled catalyst-free growth of nanowires. |
| Databáze: | OpenAIRE |
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