Nitrogen function of aluminum-nitride codoped ZnO films deposited using cosputter system

AlN codoped ZnO films were deposited on sapphire substrates at low temperature using a cosputter system under various N₂/(N₂ + Ar) flow ratios. To investigate the nitrogen function, the ratio of nitrogen ambient was varied during cosputtering. AlN codoped ZnO films with various crystallographic structures and bonding configurations were measured. With an adequate nitrogen atmosphere deposition condition and postannealing temperature at 450 °C, the p-type conductive behaviors of AlN codoped ZnO films were achieved due to the formation of Zn-N bonds. According to the low-temperature photoluminescence spectra, the binding energy (E_A) of 0.16 eV for N acceptors can be calculated. Using time-resolved photoluminescence measurement, the carrier lifetime in AlN codoped ZnO films increases due to the reduction of oxygen vacancies caused by the occupation of adequate nitrogen atoms.