Effects of Al doping on the optical and electrical properties of pre-synthesized ZnO powders by solid state method

White and fluffy Al-doped zinc oxide powders were fabricated using ZnO and Al(C ₃H ₇O) ₃ powders by a solid statemethod.The effects ofAl doping onmicrostructure, electrical and optical properties were systematically studied. XRDand Raman results showthat theAl-doped powders have a pure hexagonal wurtzite structure. The resistivity of ZnO could be decreased from 10 ⁸ to 10 ² ω cm with the Al doped concentration of 3 at.%. Meanwhile, the obtained powders exhibited high diffuse reflectance in visible region, intense UV emission without deep level emission and good environmental stability. Results reveal that the optical property of the powders has an intimate relationship with the electrical property. The decline of the diffuse reflectance at visible wavelengths and the strong IR absorption were due to the increase of the free electron concentration. Al doping leads to quenching of defect related visible band emission, and we surmise that the defect centers are mainly related to oxygen vacancies (V _O) and zinc vacancies (V _Zn). Al doping mechanism was also tentatively explored.