The Study of Energy Band Gap of Al,Inj,Gai,_J,N Quaternary Alloys Using UV-VIS Spectroscopy

摘要

Optical characterizations have been performed on high-quality quaternary Al_xIn_yGa_(1-x-y)N thin films using UV-VIS spectroscopy at room temperature. The Al_xIn_yGa_(1-x-y) films were grown on c-plane (0001) sapphire substrates with AIN as buffer layers using molecular beam epitaxy (MBE) technique with aluminum (Al) mole fraction x ranging from 0.0 to 0.2 and constant indium (In) mole fraction y = 0.1. The UV-VIS measurements indicated that the energy band gap of the quaternary films increases with increasing Al composition from 0.05 to 0.2. This trend is expected since the incorporation of Al increases the energy band gap of ternary In0.1Ga0.90N (3.004eV). We have also investigated the bowing parameter of the variation of energy band gaps and found it to be very sensitive on Al content. A value of b=7eV has been obtained for our quaternary Al_x In_yGa_(1-x-y)N alloys.