Sains Malaysiana 42(12)(2013): 1811–1814

 

Clusters of GaAs Prepared by Quantum Mechanical DFT and the Nanowire Raman Spectra

(Penyediaan Kluster GaAs Menggunakan DFT Kuantum Mekanik dan

Spektrum Raman Nano Wayar)

 

 

AHMAD NAZRUL ROSLI1*, HASAN ABU KASSIM2 & KESHAV N. SHRIVASTAVA2

 

1Faculty Science and Technology, Universiti Sains Islam Malaysia (USIM), 71800 Nilai,

Negeri Sembilan, Malaysia

 

2Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia

 

Received: 19 November 2012/Accepted: 1 April 2013

 

ABSTRACT

We studied the clusters of GaAs by using the density functional theory simulation to optimize the structure. We determined the binding energy, bond lengths, Fermi energy and vibrational frequencies for all of the clusters. We use the Raman data of nanowires of GaAs to compare our calculated values with the experimental values of the vibrational frequencies. The nanowire of GaAs gives a Raman line at 256 cm-1 whereas in the bipyramidal Ga2As3 the calculated value is 256.33 cm-1. Similarly 285 cm-1 found in the experimental Raman data agrees with 286.21 cm-1 found in the values calculated for Ga2As2 (linear) showing that linear bonds occur in the nanowire. The GaAs is found in two structures zinc-blend as well as wurtzite structures. In the nanowire mixed structures as well as clusters are formed.

 

Keywords: Cluster; DFT; GaAs; raman spectra; vibrational frequencies

 

ABSTRAK

Kluster GaAs menggunakan simulasi teori fungsi ketumpatan untuk mengoptimumkan struktur telah dikaji. Tenaga ikatan, panjang ikatan, tenaga Fermi dan frekuensi getaran untuk semua kluster telah diperoleh. Kami menggunakan data Raman untuk nano wayar bagi GaAs untuk membuat perbandingan frekuensi getaran antara hasil pengiraan kami dengan hasil eksperimen. Garis Raman bagi GaAs nano wayar adalah pada 256 cm-1 manakala hasil pengiraan kami untuk Ga2As3 dwi-piramid adalah 256.33 cm-1. Begitu juga dengan nilai 285 cm-1 yang dijumpai pada data eksperimen Raman yang setara dengan hasil pengiraan kami 286.21 cm-1 yang dijumpai daripada pengiraan untuk Ga2As2 (linear) yang menunjukkan ikatan linear wujud dalam nano wayar. GaAs ditemui dalam dua struktur iaitu zink-blende serta dalam struktur wurtzite. Dalam nano wayar, struktur campuran dan kluster didapati wujud.

 

Kata kunci: DFT; frekuensi getaran; GaAs; kluster; spektra Raman

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*Corresponding author; email: anazrul84@yahoo.com

 

 

 

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