Structural and linear and nonlinear optical properties of Zn_1-xAl_xO (0≤x≤010) thin films fabricated via pulsed laser deposition technique

Abstract

The effect of Al doping on linear and nonlinear optical properties of pulsed laser deposited (PLD) Zn1-xAlxO (AZO) thin films is reported. The increase in 002 peak in X-ray diffraction pattern up to x = 0.05 is indicative of improvement in the wurtzite phase and was also confirmed by enhancement in E2 (high) peak at 438 cm−1 of Raman spectra. The increase in the blue shift in the band gap up to x = 0.05 suggests the Burstein Moss effect. The red shift in the band gap for x>0.05 can be interpreted due to the band gap renormalization as a result of many body interaction effects. The two photon absorption coefficients (β) and nonlinear refractive indices (n2) measured via z-scan measurement were found to be in the range of 3.4-8.0 cm/W and (1.0-5.2) × 10−4 cm2/W for x = 0.00-0.10 respectively. An attempt is made to correlate the linear and nonlinear optical behavior and crystal structure as a function of level of Aluminum doping (x).