Ga and In incorporation rates in Ga 1  x In x As growth by chemical beam epitaxy D. Ghita a , J. Plaza b , M. Sa ´ nchez c , A. Climent-Font d , B.J. Garcı ´a a,n a Laboratorio de Electro ´nica y Semiconductores, Departamento de Fı ´sica Aplicada, Universidad Auto ´noma de Madrid, 28049 Madrid, Spain b Departamento de Investigacio ´n, Centro de Investigacio ´n y Desarrollo de la Armada, Arturo Soria 289, 28033 Madrid, Spain c Facultad de Fı ´sica, Universidad de La Habana, San La ´zaro y L, Vedado, 10400 La Habana, Cuba d Departamento de Fı ´sica Aplicada and Centro de Micro-Ana ´lisis de Materiales, Universidad Auto ´noma de Madrid, 28049 Madrid, Spain article info Article history: Received 25 October 2010 Received in revised form 23 November 2010 Accepted 5 December 2010 Communicated by: K.H. Ploog Available online 9 December 2010 Keywords: A3. Chemical beam epitaxy B2. Semiconducting III–V materials B2. Semiconducting ternary compounds abstract GaAs, InAs and Ga 1 x In x As layers were grown by chemical beam epitaxy (CBE) using triethylgallium, trimethylindium and tertiarybutylarsine as precursors for Ga, In and As, respectively. The growth rate during the homoepitaxial growth of GaAs and InAs, deduced from the frequency of reflection high-energy electron diffraction intensity oscillations, was used to calibrate the incorporation rates for the III elements. The In content of the Ga 1x In x As layers was measured by Rutherford backscattering spectro- metry and compared with the value predicted from the above calibration data; while the measured In mole fraction is close to the predicted value for the samples grown for low In to Ga flux ratios (x o0.2), the In incorporation is enhanced for larger values of this ratio. The results obtained on layers grown at different substrate temperatures show that In mole fraction is almost constant at growth temperatures in the range 400–500 1C, but a strong dependence on the substrate temperature has been found outside this range. The above results, not observed for samples grown by solid source molecular beam epitaxy, indicate that some interaction between Ga and In precursors at the sample surface could take place during the growth by CBE. & 2010 Elsevier B.V. All rights reserved. 1. Introduction Ga 1x In x As is an important and well known III–V compound semiconductor for electronic and optoelectronic applications; the addition of either P or N to this material allows the growth of the quaternary semiconductors Ga 1x In x As 1y P y and Ga 1x In x As 1y N y . The first of the above quaternaries is nowadays the basis of the family of semiconductor optoelectronics suitable for infrared optical commu- nications, allowing the fabrication of light emitters and receivers [1] lattice-matched to InP substrates. More recently, devices based on Ga 1 x In x As 1 y N y appear to become an alternative family for infrared semiconductor optoelec- tronics allowing the growth of lattice-matched layers [2] on GaAs substrates while promising even longer wavelength operation and better performance [3,4]. The main aspects of the growth of Ga 1 x In x As by conventional solid source molecular beam epitaxy (MBE) are now quite well known, allowing the growth of Ga 1 x In x As layers with a well controlled In mole fraction for substrate temperatures T s at which In re-evaporation at the sample surface is not significant [5,6] (T s o520 1C). The addition of P is usually achieved using valve-cracked P sources, while N incorporation is usually done by radio-frequency (RF) plasma assisted cells, limiting both the N flux and RF power to avoid ion induced damage. The growth of Ga 1 x In x As by chemical beam epitaxy (CBE) using gaseous precursors [7] is also interesting from the point of view of its compatibility with N and P precursors allowing the growth of the above quaternaries; for this purpose, a substrate temperature window of compatibility [8,9] has to be found in order to achieve the reaction and dissociation of precursors on the sample surface. We show in this work the results obtained on the growth of Ga 1 x In x As using trimethylindium (TMIn), triethylgallium (TEGa) and teriarybutylarsine (TBAs) as precursors in a CBE system. 2. Experimental Samples were grown on a modified MBE system previously described [10], including two gas injectors or cells. Precursors using the same cell are mixed in its high pressure section (about 10 2 torr), obtaining a good flux homogeneity over the sample surface. Flux control is done by pressure regulation, ensuring a crosstalk lower than 2% between lines connected to the same gas cell. TMIn and TEGa precursors were supplied through a low temperature gas cell (T cell ¼ 80 1C) heated only to avoid gas condensation. Because the use of uncracked TBAs can limit the growth rate due to its low decom- position rate at the growth temperatures [11], a second high tempera- ture cracking gas cell (T cell ¼ 700 1C) was used for TBAs. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jcrysgro Journal of Crystal Growth 0022-0248/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2010.12.013 n Corresponding author. Tel.: + 34 914974915. E-mail address: basilio.javier.garcia@uam.es (B.J. Garcı ´a). Journal of Crystal Growth 314 (2011) 48–52