Band gap variation in laser irradiated polytypic crystals of cadmium iodide
Department of Physics and Astrophysics, University of Delhi, Delhi-110 007, India
Revised: 6 August 1997
Accepted: 15 September 1997
Published online: 15 April 1998
Highly purified single crystals of cadmium iodide obtained through repeated zone refining have been subjected to laser beam exposure (Argon ion laser), both for various time durations and to various beam intensities, and then subjected to band gap determination by UV spectroscopy. The band gap has been found to decrease gradually with increase in the laser beam intensity, whereas its variation with increase in time of exposure shows an unusual behaviour such that it initially falls sharply followed by a gradual rise back to its original value. The results have been analysed and interpreted in terms of indirect band gap character of the material and an unusual variation in phonon frequency. The interpretation is well supported by X-ray diffraction and scanning electron microscopy (SEM) studies.
PACS: 78.20.-e – Optical properties of bulk materials and thin films / 78.70.-g – Interactions of particles and radiation with matter
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998