Journal of Crystal Growth 240 (2002) 333–339 Dynamical faceting and nanoscale lateral growth of GaAs by molecular beam epitaxy S.C. Lee a,b, *, L.R. Dawson a,b , S.R.J. Brueck a,b,c a Center for High Technology Materials, The University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106, USA b Department of Electrical and Computer Engineering, The University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106, USA c Department of Physics and Astronomy, The University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106, USA Received 12 November 2001; accepted 19 December 2001 Communicated by A.Y. Cho Abstract Dynamical faceting during homoepitaxial growth of GaAs on nanoscale-patterned surfaces by molecular beam epitaxy is examined. Selective deposition on open GaAs(100) surfaces with lateral dimensions ranging from 130 to 250nm, separated by 15–80nm-wide (25-nm-thick) SiO 2 stripes aligned along the ½0 % 11 direction results in facet formation and lateral growth over the SiO 2 mask. At the early stage of growth, (311) facets appear on sidewalls near the boundary between an open GaAs surface and SiO 2 mask, these are replaced by (111) facets starting from SiO 2 boundaries as growth continues. After complete replacement, growth proceeds laterally in the direction perpendicular to ½0 % 11 retaining the (111) facets until coalescence occurs between adjacent triangular cross-sectioned GaAs stripes. Nanoscale fabrication nonuniformity results in dynamical formation and retention of multiple (3 11) facets even for growth thicknesses much greater than the thickness of the SiO 2 mask stripes. This dynamical faceting is interpreted by minimization of total surface free energy based on equilibrium crystal shape, in qualitative agreement with our experimental results. r 2002 Elsevier Science B.V. All rights reserved. PACS: 68.55.B Keywords: A1. Faceting; A2. Lateral growth; A3. Molecular beam epitaxy; A3. Selective epitaxy 1. Introduction Nanoscale-patterned (nanopatterned) growth is attracting considerable interest because of the possibility of a deterministic alignment of quan- tum dots (QDs) with improved size uniformity and of migration-assisted selective growth in molecu- lar beam epitaxy (MBE) [1,2]. For 1-dimensional (1-D) patterning, as the lateral dimension of the open substrate surface, d ; is decreased to a scale comparable to or smaller than the thickness, t, of an epilayer, faceting will determine the overall shape of a selectively grown epilayer. This faceting provides a powerful new approach to the forma- tion of nanopatterned surfaces that avoids many *Corresponding author. Center for High Technology Mate- rials, The University of New Mexico, 1313 Goddard SE, Albuquerque, NM 87106, USA. E-mail address: sclee@chtm.unm.edu (S.C. Lee). 0022-0248/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0022-0248(02)00867-9