Raman scattering and FTIR studies of 100 MeV Fe⁹⁺ ion-irradiated gallium phosphide

Abstract

Gallium phosphide samples have been irradiated with 100 MeV ⁵⁶Fe⁹⁺ ions for various ion fluences varying from 1×10¹¹ to 1×10¹⁴ cm⁻² at room temperature. Irradiated samples were characterized by Raman scattering and Fourier transform infrared techniques. The stress estimated from the Raman peak shift for the ion fluences of 1×10¹², 5×10¹², 1×10¹³, 5×10¹³ and 1×10¹⁴ cm⁻² were found to be 222, 280, 290, 355 and 522 MPa, respectively. The average crystallite size obtained by analyzing Raman spectra with phonon confinement model was decreased with the increase in the ion fluence. The electron–phonon coupling strength estimated from the first- and second-order longitudinal optical modes of Raman spectra was found to decrease as the crystallite size became smaller in the irradiated samples. The observed interference fringes in the Fourier transform reflectance spectra of irradiated gallium phosphide indicate the presence of disorder and defects in the surface region of irradiated gallium phosphide.

Keywords:

• swift iron ion
• gallium phosphide
• Raman scattering
• FTIR

Acknowledgements

The authors are thankful for the financial support received from the IUAC, New Delhi, under the UFUP-35320 scheme, and to the members of the Pelletron group for providing the excellent iron ion beam.