A novel approach for codoping in ZnO by AlN

In the present work, we have illustrated a new idea of codoping in ZnO with AlN as codopant to achieve p-ZnO. ZnO films doped with different concentrations of AlN were grown by RF magnetron sputtering. The AlN doped ZnO (ANZO) films grown on sapphire substrate were subjected to X-ray diffraction (XRD), reflectance measurements, Hall measurements, atomic force microscopy (AFM) and energy dispersive spectroscopy (EDS) analysis. XRD analysis reveals that all films have grown in the form of hexagonal wurtzite structure with (002) preferential orientation. The FWHM of (002) peak decreases till 1 mol% of AlN and increases for further addition of AlN indicating the incorporation of more impurities (dopants). The reflectance measurements suggest that the reflectance decreases at lower concentration and increases above 1 mol% of AlN in the visible region ranging from 400 to 800 nm. Hall measurements show that all the films are n-type. The electron concentration increases initially and then decreases for further addition of AlN (>1 mol%) suggesting the incorporation of nitrogen into the film at higher concentrations of AlN. The presence of N in the films is further confirmed by EDS analysis. The rms surface roughness measured by AFM decreases exponentially with dopant concentration. The figure of merit increases upon codoping with AlN.