P-type ZnO thin films achieved by N+ ion implantation through dynamic annealing process

Abstract

ZnO thin films were grown on sapphire (0001) substrates by pulsed-laser deposition at 700 °C. 70 keV N+ ion implantation was performed under various temperatures and fluences in the range of 300−460 °C and 3.0×1014−1.2×1015 cm−2, respectively. Hall measurements indicate that the ZnO films implanted at 460 °C are p-type for all fluences used herein. Hole-carrier concentrations lie in the range of 2.4×1016−5.2×1017 cm−3, hole mobilities in the range of 0.7−3.7 cm2 V−1 s−1, and resistivities between 18−71 Ωcm. Transmission-electron microscopy reveals major microstructural differences between the n-type and p-type films. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder.