Study of Electrical and Optical Properties of Al-doped ZnO Nanoparticles*

ZnO-based transparent conducting oxide has become a promising material in the replacement of ITO due to its large band gap (Eg =3.37 eV) with high transmittance and availability in the nature. Naturally, due the oxygen vacancy ZnO is a n-type material. However, it has very low electrical conductivity which makes difficult to use it as a conducting layer. In this work, opto-electronic properties are tuned by doping Zn²⁺ with a trivalent Al atom in ZnO. With the doping of Al³⁺, the total no of charge carrier increases, so conductivity of the resultant material escalates. The sol-gel method has been used to prepare Al doped ZnO NPs. AlCl₃.6H2O were added in 0.5 M Zinc nitrate solution until dopant concentration become 5% and reacted with the aqueous solution of NaOH until the pH becomes 12.50. The final solution was used for spin coating on the glass substrate. After spin coating, the sample was put into a microwave to synthesize Al doped ZnO NPs at room temperature. The structural, composition and surface properties were investigated by XRD, Raman spectroscopy, and SEM-EDX. The optical properties have been investigated using PL and UV-VIS spectroscopy. I-V curve & hall measurement confirms the Al doping into ZnO NPs crystal.