Investigation on the ZnO:N films grown on (0001) and (0 0 0 (1)over-bar) ZnO templates by plasma-assisted molecular beam epitaxy

Nitrogen-doped ZnO films (ZnO:N) were grown on (0 0 0 1) and (0 0 0 (1) over bar) ZnO templates by plasma-assisted molecular beam epitaxy (PA-MBE). High nitrogen concentration (> 5 x 10(20)/cm(3)) was achieved from ZnO:N/(0 0 0 1)ZnO films, while relatively low nitrogen concentration (similar to 10(19)/cm(3)) was observed from ZnO:N/(0 0 0 (1) over bar )ZnO layers at the same growth temperature (T-g). High-resolution X-ray diffraction (HRXRD) revealed considerable lattice deformation. At T-g=300 degrees C, the c-lattice expansion in ZnO:N/(0 0 0 1)ZnO film is almost 36% larger than that in ZnO:N/(0 0 0 (1) over bar )ZnO due to the high nitrogen concentration in the film. Electron concentration of the ZnO:N/(0 0 0 1)ZnO films gradually decreases down to similar to 10(16)/cm(3) as the nitrogen concentration increases. Moreover, donor-acceptor-pair emission dominates the photoluminescence (PL) spectrum (3.23 eV) of ZnO:N/(0 0 0 I)ZnO films grown at 300 degrees C and that emission is 3.1 times stronger than that of ZnO: N/(0 0 0 (1) over bar )ZnO. (c) 2008 Published by Elsevier B.V.