Anisotropy of selective epitaxy in nanoscale-patterned growth: GaAs nanowires selectively grown on a SiO{sub 2}-patterned (001) substrate by molecular-beam epitaxy
- Center for High Technology Materials and Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States)
Anisotropic selective epitaxy in nanoscale-patterned growth (NPG) by molecular-beam epitaxy is investigated on a 355 nm period two-dimensional array of circular holes fabricated in a 30-nm-thick SiO{sub 2} film on a GaAs(001) substrate. The hole diameter ranged from 70 to 150 nm. The small hole diameter and the very thin masking layer stimulated lateral growth over the SiO{sub 2} surface at an early stage of selective epitaxy on this patterned substrate. Lateral overgrowth associated with selective epitaxy, however, did not proceed isotropically along the circular boundary between the open substrate surface and the SiO{sub 2} mask. There was preferential growth direction parallel to <111>B. This anisotropy in the selective epitaxy resulted in the formation of a nanoscale, nontapered, straight-wire-type epitaxial layer (GaAs nanowires), which had a length of up to 1.8 {mu}m for a nominal 200 nm deposition. Every GaAs nanowire had a hexagonal prismatic shape directed along <111>B and was surrounded by six (110) sidewalls. The anisotropy of selective epitaxy and faceting in NPG were affected by the profile of the SiO{sub 2} mask and are interpreted using a minimization of the total surface energy for equilibrium crystal shape.
- OSTI ID:
- 20714159
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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