Effects of N doping on ZnO thin films grown by MOVPE

Effects of N doping on zinc oxide (ZnO) thin films by metal organic vapor phase epitaxy (MOVPE) using diethyl zinc (DEZn) and O2 precursors and NH3 as the doping source have been studied. N-doped ZnO thin films were deposited on c-plane sapphire substrates with NH3 flow rates from 0.2% to 4% during growth. Highly resistive ZnO thin films with p-type carrier concentrations of 4.24×1014 cm−3 and mobility of 16.55 cm2/Vs were obtained. Resistivity for the as-grown films on the order of 2.3×106 Ω cm was observed. The PL results of the N-doped ZnO show suppression of the band-edge luminescence and two broad peaks centered at 480 and 600 nm attributable to deep N acceptor luminescence were seen. Rapid thermal annealing at 800 °C in N2 ambient turned all the N-doped ZnO films, irrespective of doping concentration, to highly conductive n-type with carrier concentration on the order of 5.92×1018 cm−3, mobility on the order of 34.91 cm2/Vs and resistivity of 0.09 Ω cm.