Damage formation and Er structural incorporation in m-plane and a-plane ZnO

Abstract

The various crystallographic orientations in semiconductors as ZnO exhibit different resistivity under the ion beam irradiation/implantation. Study of the various crystallographic orientations is mandatory for nano-structured semiconductor system development. This paper reports on the implantation damage build-up, structural modification and Er dopant position in a-plane and m-plane ZnO implanted with Er+ 400 keV ions at the ion fluences 5 × 1014, 2.5 × 1015, 5 × 1015 cm−2 and subsequently annealed at 600 °C in O2 atmosphere using Rutherford Back-Scattering spectrometry (RBS) in channelling mode as well as using Raman spectroscopy. Strongly suppressed surface damage formation was observed in both crystallographic orientations compared to the deep damage growth with the increased ion implantation fluence. More progressive damage accumulation appeared in m-plane ZnO compared to a-plane ZnO. Simultaneously, the strong Er out-diffusion depth profile in m-plane ZnO accompanied by the damage accumulation at the surface was observed after the annealing. Contrary, the surface recovery accompanied by Er concentration depth profiles keeping a normal distribution with a small maximum shift to the surface was observed in a-plane ZnO. Different structure recovery and Er behaviour was evidenced in a-plane and m-plane ZnO by RBS-C, moreover Raman spectroscopy proved a lower damage at higher ion fluences introduced in a-plane ZnO compared to m-plane. The structure modifications were discussed in connection with a damage accumulation and Er concentration depth profile shape in various ZnO crystallographic orientations in as-implanted and as-annealed samples.