L.H. Zhang

Electrical and optical properties of ZnO films sequentially implanted with P ions

ZnO thin films deposited on fused silica glass substrates were sequentially implanted with P ions in terms of different energy/fluence combinations, i.e. 150 keV/1.5 × 1015 ions cm−2, 80 keV/5.5 × 1014 ions cm−2 and 35 keV/2.5 × 1014 ions cm−2, or were singly implanted with 150 keV P ions at a fluence of 1.5 × 1015 ions cm−2. X-ray diffraction, photoluminescence, Hall effect and electrical resistivity measurements were performed to characterize the properties of the films. The results show that both the unimplanted and single-P-ion-implanted films exhibit semi-insulating properties, while the sequentially implanted film shows p-type conductivity with a low carrier concentration. After annealing at 500 °C, hole concentration increases distinctly in the sequentially implanted film, and the other films show n-type conductivity. Further increasing annealing temperature to 700 °C, all the films show large resistance. Moreover, structures and optical properties of these films have also been systematically investigated. It seems that P substitutes O (PO) and/or zinc vacancies (VZn) play an important role for p-type conductivity in sequentially implanted films.