Effects of 200 MeV silver ion irradiation on the optical properties of gallium phosphide

Abstract

The effects of irradiation of 200 MeV silver ions on gallium phosphide with various fluences varying from 1×10¹¹ to 2×10¹³ ions cm⁻² were investigated with spectroscopic ellipsometry and atomic force microscopy (AFM) measurements. The refractive index and extinction coefficient measured in ultraviolet, visible and infrared regimes were found to vary with ion fluence. The optical energy band gaps of the irradiated samples estimated from the absorption coefficient were found to vary from 2.27 to 2.19 eV with increase in ion fluence. The surface morphology of non-irradiated and samples irradiated with various fluences was examined using AFM. As ion fluence increases, the nano-size hills were developed on the surface of gallium phosphide. The shape, size, density of hills and r.m.s. roughness of the samples irradiated with various ion fluences were found to depend on the ion fluence.

Keywords:

• swift silver ion
• gallium phosphide
• spectroscopic ellipsometry
• atomic force microscopy

Acknowledgements

The authors are thankful for the financial support received from Inter University Accelerator Centre (IUAC), New Delhi, and also to the members of Pelletron group for providing excellent silver ion beams.