Raad Chegel - Physics Department, Faculty of Science, Malayer University, Malayer, Iran
Somayeh Behzad - Physics Department, Faculty of Science, Razi University, Kermanshah, Iran
Rostam Moradian - Physics Department, Faculty of Science, Razi University, Kermanshah, Iran

The linear optical absorption of zigzag single walled boron nitride nanotubes (BNNTs) in the tight binding approximation are studied. We divided the zigzag BNNTs into three groups and investigated their optical absorption spectrum in photon energy ranges E < 5, 7 < E < 7.5 and E > 7.5 eV. We found that in lower energies, E < 5 eV, all groups show different behaviors while in the higher energies, 7 < E < 7.5 and E > 7.5 eV, their behaviors depend on their even or odd nanotube index. Also we found that in the higher energies range 7 < E < 7.5 eV all tubes have two distinct peaks where the second peak energy position is approximately constant and it is independent of the nanotube diameter. Also we found that increasing tubes diameter lead to red shift for all peaks. Our results are in good agreement with the experimental results.

Nanostructures, Semiconductors, Optical absorption spectrum, Tight binding model