Selective growth of GaAs by HVPE: keys for accurate control of the growth morphologies

GaAs selective growth experiments were carried out on (0 0 1) GaAs-patterne d substrates by HVPE. Mesas grown on [1 1 0] and [1 (1) over bar 0] oriente d stripes exhibited various morphological profiles bounded by the low growt h rate faces (0 0 1), (1 1 0), (1 1 1)A and (1 1 1)B, depending on the III/ V ratio in the vapour phase, on the supersaturation and the growth temperat ure. The shape of the mesas results from the hierarchy of the growth rates of the low index faces. The latter growth rates were independently determin ed on un-masked substrates. Kinetic Wulff constructions were then built by referring to these growth rates. A good agreement was obtained between the morphologies of the selectively grown mesas and the constructions built fro m the only knowledge of the growth rate anisotropy, demonstrating that HVPE growth is mainly governed by surface kinetics. Qualitative growth mechanis ms involving As and GaCl net adsorption fluxes as well as chlorine desorpti on kinetics are proposed for the various low index faces. (C) 2001 Elsevier Science B.V. All rights reserved.