Investigating mechanism of photo refractivity in Mg substituted ZnO thin films using pump and probe technique

Abstract

In the current investigation magnesium (Mg) has been incorporated in the ZnO matrix to induce photo refractivity thereby adding an extra dimension to its already present multi-functionality. Undoped and MgxZn1-xO (x = 0.25, 0.30, 0.35, 0.40, 0.45) thin films have been grown using Chemical Solution Deposition (CSD) technique. Obtained X-Ray Diffraction (XRD) spectra exhibits a slight shift in the peak value along (002) plane whereas UV–visible spectra indicates corresponding widening of ZnO band gap values (3.24–3.64 eV) with increase in Mg content. Mg substituted ZnO films were then investigated for their ferroelectric properties using a P-E hysteresis loop tracer. It was noted that ZnO film with 35 % Mg content (x = 0.35) exhibited the high values for saturation (Ps = 1.8 μC/cm2) and remnant (Pr = 0.7 μC/cm2) polarization. Hence the ZnO with same Mg concentration was investigated for nonlinear optical properties (two wave mixing phenomenon) using pump and probe technique. In order to enhance the beam amplification gain and impart stability Au micro-dots were thermally evaporated onto MgxZn1-xO (x = 0.35) films. The maximum beam amplification gain was noted to shoot up to 2.7 post patterning of MgxZn1-xO (x = 0.35) film surface by Au micro-dots.