Dynamical effective charges and dielectric constants in the pentanary alloy Ga x In 1x P y Sb z As 1y z lattice matched to InAs and GaSb H. Baaziz a , Z. Charifi a , N. Bouarissa b, * a Physics Department, Faculty of Science and Engineering, University of Msila, 28000 Msila, Algeria b Department of Physics, Faculty of Science, King Khalid University, Abha, P.O. Box 9004, Saudi Arabia Received 2 March 2005; accepted 24 July 2005 Available online 15 August 2005 Abstract Pseudo-potential formalism under the virtual crystal approximation combined with the Harrison bond-orbital model is applied to the pentanary alloy Ga x In 1x P y Sb z As 1y z lattice matched to InAs and GaSb to predict its lattice dynamic and dielectric properties as a function of P mole fraction. To the best of our knowledge, such a study has never been previously reported for pentanary alloys. Results are presented for the polarity, ionicity, transverse effective charge, static and high-frequency dielectric constants and showed generally reasonable agreement with the experimental data which are only available for the binary compounds of interest. The results suggest that, for a proper choice of the substrate, x and z , Ga x In 1x P y Sb z As 1y z could provide more diverse opportunities to achieve desired dynamical effective charges and dielectric constants aiding therefore in the discovery of new materials with desired properties. D 2005 Elsevier B.V. All rights reserved. PACS: 71.20.-b Keywords: Transverse effective charge; Dielectric constants; Pentanary; Lattice matched alloys 1. Introduction There has been considerable interest in the III–V multi- component semiconductor alloys for many applications, such as high-speed electronic and long-wavelength pho- tonic devices [1–4]. One significant reason for this interest is the ability to synthesize materials either with a fixed lattice constant and a variable range of energy band gaps or, with a constant energy band gap and a variable lattice constant [5–8] which could lead to new semiconductor materials with desired band gaps over a wide spectral range. While extensive experimental and theoretical studies on ternary semiconductor alloys have been reported [2– 4,9–15], detailed investigations for quaternary semicon- ductor alloys have not been actively explored except for a few of them [2–4,6–8,16–20]. There are no experimental reports on the pentanary alloys, to the best of our knowledge. However, on the theoretical side, Shim and Rabitz [6,21,22] have reported the first investigation on the electronic and structural properties of the pentanary alloys (with three composition variables) using the universal tight binding model based on a modified pseudo-cell. Pseudo- potential calculations of electronic and positronic proper- ties of pentanary alloys have also been recently reported [23,24]. The dynamical effective charges and dielectric constants are important parameters in semiconductors. The effective charge of the ions is a fundamental quantity in the study of the dynamics of crystalline lattices which is implicitly related to the bond polarity of the material and may be taken as a measure of its ionicity. On the other hand, the concept of the dielectric behavior of solids is important for several electron-device properties [25]. In spite of the importance of these quantities, only limited studies have been reported on them in III – V ternary and quaternary alloys [10,14,18]. To the best of our knowledge, the dynamical effective charges 0167-577X/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2005.07.067 * Corresponding author. E-mail address: N _ Bouarissa@yahoo.fr (N. Bouarissa). Materials Letters 60 (2006) 39 – 43 www.elsevier.com/locate/matlet