Aluminum Doping Contents Dependent Photoluminescence and Resistivity of ZnO Nanofilms

Using sol–gel spin-coating technique Al-doped ZnO nanofilms (AZONFs) were made on Si(100) substrates and characterized. The obtained nanofilms were annealed at 500 °C for 3 h in air. The effects of changing Al doping level (0 to 5 at%) on the structures, morphologies, electrical and photoluminescence characteristics of the nanofilms were evaluated. The XRD patterns of the AZONFs confirmed the formation of wurtzite hexagonal ZnO lattice with preferred growth along (101) lattice plane. In addition, the c-axis orientation of the AZONFs became weaker with the increase in Al doping contents. The surface morphologies, structures, electrical and optical properties of the AZONFs were found to be very sensitive to the Al contents changes. The nanofilm prepared with 1 at% of Al displayed lowest resistivity of 4.238 × 10⁻³ Ω.cm measured by the four-point probe method. The optical band gap energy (increased from 3.22 to 3.304 eV) and carrier mobility of the AZONFs were improved with the increase in Al contents. The proposed AZONFs may be advantageous for various high performance optoelectronic device applications. (paper)