* Corresponding author. Tel.:#33 5 62 25 78 93; fax: #33 5 62 25 79 99; e-mail: ponchet@cemes.fr. Journal of Crystal Growth 201/202 (1999) 252}255 Elastic relaxation phenomena in compressive Ga  In  As grown on (0 0 1) and (1 1 3)B InP at low lattice mismatch D. Lacombe, A. Ponchet*, S. Fre H chengues, V. Drouot, N. Bertru, B. Lambert, A. Le Corre  CEMES-CNRS, BP 4347, 31055 Toulouse Cedex, France  Laboratoire de Physique des Solides (INSA), BP 144, 35043 Rennes, France  France-Te & le & com, CNET, 2 avenue P. Marzin, 22307 Lannion Cedex, France Abstract Compressively strained layers of Ga  In  As were grown on InP(0 0 1) and (1 1 3)B by gas source MBE (lattice mismatch of 1.8%). For a growth temperature of 5003C, islands were obtained on the (1 1 3)B substrate. On the (0 0 1) substrate, the deposit formed a quasi-2D layer hollowed by isolated valleys. At higher growth temperature, single wires had begun to develop between adjacent valleys. It is shown that the direct formation of 3D islands is favoured on (1 1 3)B because they can be bounded by low index facets, while on (0 0 1) the formation of valleys in a 2D layer appears as a precursor state of a 3D morphology.  1999 Elsevier Science B.V. All rights reserved. Keywords: Ga  In  As; Lattice mismatch; Elastic relaxation 1. Introduction Three-dimensional (3D) growth modes are com- monly reported in the strained layers, especially in the III}V compounds. It is well known that they allow a relaxation of the elastic energy. However, di!erent growth morphologies can be observed, depending on the lattice mismatch a/a, and growth parameters. In the InP-based systems, a mismatch above 2}3% (compressive stress) gener- ally induces the growth of coherent islands, while low mismatched layers are considered as 2D [1]. Tensile layers are generally less stable than compressive ones even for small a/a, !0.5% for instance [2]. The formation of valleys or holes instead of islands is sometime considered as charac- teristic of the relaxation of tensile layers as opposite to compressive ones [3]. However, the reason why 3D islands or holes (or valleys) are formed is not completely understood. On the other hand, it was shown that islands are obtained on (1 1 3)B sub- strate even for low a/a [4]. We present here some results concerning Ga  In  As layers grown on (0 0 1) and (1 1 3)B InP substrates under compressive stress (a/a"1.8%), in order to examine how a 3D mor- phology can take place at this relatively low lattice mismatch. 0022-0248/99/$ } see front matter  1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 0 2 4 8 ( 9 8 ) 0 1 3 3 2 - 3