Unidirectional variation of lattice constants of Al–N-codoped ZnO films by RF magnetron sputtering

Al–N-codoped ZnO films were fabricated by RF magnetron sputtering in the ambient of N2 and O2 on silicon (1 0 0) and homo-buffer layer, subsequently, annealed in O2 at low pressure. X-ray diffraction (XRD) spectra show that as-grown and 600 °C annealed films grown by codoping method are prolonged along crystal c-axis. However, they are not prolonged in (0 0 1) plane vertical to c-axis. The films annealed at 800 °C are not prolonged in any directions. Codoping makes ZnO films unidirectional variation. X-ray photoelectron spectroscopy (XPS) shows that Al content hardly varies and N escapes with increasing annealing temperature from 600 °C to 800 °C.