tailieunhanh - Báo cáo vật lý: "TEMPERATURE DEPENDENCE OF RAMAN SPECTRA OF POROUS GAP"

Tuyển tập các báo cáo nghiên cứu khoa học trên tạp chí khoa học vật lý quốc tế đề tài: TEMPERATURE DEPENDENCE OF RAMAN SPECTRA OF POROUS GAP | Journal of Physical Science Vol. 18 2 49-57 2007 49 TEMPERATURE DEPENDENCE OF RAMAN SPECTRA OF POROUS GAP Khalid M. Omar1 Zahid H. Khan2 . Soni3 and . Abbi3 1School of Physics Universiti Sains Malaysia 11800 USM Pulau Pinang Malaysia department of Physics Jamia Millia Islamia 110025-New Delhi India department of Physics Indian Institute of Technology 110016-New Delhi India Corresponding author khalhadithi@ Abstract Nanostructure gallium phosphate was fabricated using laser-induced etching LIE process and the characteristic dimensions were determined with phonon confinement model. The laser was also used for spectroscopic investigations. It was found that the surface phonon frequency depends on the nanocrystalline size shape and dielectric constant of the surrounding medium and the broadening Raman line was caused by the size distribution which was dependent on the etching parameters. The temperature dependent Raman scattering of porous and bulk GaP were compared. The experimental and theoretical results indicated that there was a higher degree of anharmonicity existed in the porous than in the bulk. The anharmonic constants were found to be highly size dependent and increased with decreasing dimensions. The phonon lifetimes decreased with increasing temperatures independent but both decreasing with decreasing of nanocrystals size. Keywords temperature dependence porous GaP Raman 1. INTRODUCTION In last ten years researchers have been attracted to study porous To study the properties of semiconductors requires a detailed investigation of the structure of the frame which remains after etching of the initial bulk material and the state of its surface. The properties of GaP are interesting in the initial material like Si is an indirect-gap material eV and the band structure is similar to the Si. GaP is an inert material oxidizes slightly in air and the expectation of the porous layers based on it will be more stable and is less .