Journal of Crystal Growth 248 (2003) 417–420 Investigation of the GaAs-pyramids overgrowth using MOCVD D. Gregu$ sov ! a a, *, V. Cambel a , R. K ! udela a , J. $ Solt " ys a , I. Kosti " e b , G. Attolini c , C. Pelosi c a Institute of Electrical Engineering, Slovak Academy of Sciences, D ! ubravsk ! a cesta 9, 842 39 Bratislava, Slovakia b Institute of Informatics, Slovak Academy of Sciences, D ! ubravsk ! a cesta 9, 842 37 Bratislava, Slovakia c MASPEC Parma, CNR, Viale delle Scienze, 431 00 Parma, Italy Abstract In this work, the epitaxial overgrowth of high and smooth GaAs mesas is presented. GaAs mesas of sidewall slope 351, 401, 451, and 551 were first prepared by wet-chemical etching in H 3 PO 4 ,H 2 O 2 ,H 2 O based solution. Then the metallorganic chemical vapour deposition was used for the mesas overgrowth. The influence of the growth conditions— temperature, V/III ratio, and growth rate—on the mesa-sidewall morphology was studied using optical microscopy, scanning electron microscopy and atomic force microscopy. We show that the sidewall quality is very high for all mesa slopes for growth rate 0.6 mm/h, V/III ratio 383, and growth temperature 6401C. Grown structures reveal strong tendency for faceting into {1 1 0} crystallographic planes. r 2002 Elsevier Science B.V. All rights reserved. PACS: 81.60.Cp; 81.15.Gh Keywords: A1. Atomic force microscopy; A1. Etching; A1. Roughening; A1. Surfaces; A3. Metalorganic vapor phase epitaxy 1. Introduction Epitaxial growth on pre-patterned compound semiconductor substrates has been studied exten- sively with the aim to obtain novel structures and to realize new semiconductor devices. Two ways have been used to prepare patterned semiconduc- tor substrates for the following epitaxial over- growth—either direct patterning of the 3D objects by wet-chemical etching or by the deposition and definition of masking materials for the selective area growth [1]. For both approaches, it is inevitable to control precisely, first, the etching process and second, the growth conditions. However, only few papers appeared on the overgrowth of large GaAs 3D objects prepared by etching. The growth on both stripe and square (0 0 1)-GaAs-mesas using mole- cular beam epitaxy (MBE) has shown that the {0 0 1} facets are on the structures always formed [2]. In Ref. [3] the influence of the growth temperature and the V/III ratio on the quality of the layer in atmospheric-pressure-MOCVD appa- ratus was investigated. *Corresponding author. Fax: +4212-5477-5816. E-mail address: elekgreg@savba.sk (D. Gregu$ sov ! a). 0022-0248/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0022-0248(02)01850-X