Low temperature growth of Si on Si(111) by gas-source MBE with rapid thermal annealing: AFM study on surface morphology

Abstract

Low temperature growth technique for gas-source molecular beam epitaxy (GS-MBE) has been proposed. This technique uses rapid thermal annealing (RTA) at regular intervals to improve defective crystallinity of the film obtained at low growth temperature (525°C). Tapping-mode atomic force microscope and reflection high energy electron diffraction were used to investigate the surfaces grown with RTA. Annealing temperature of 850°C is enough to make the 3D-surface grow at 525°C flat. Even lower annealing temperature is also effective when other parameters are fixed properly. Surface morphology is dependent on both the interval of RTA and the annealing temperature up to certain interval of RTA. The influence of the interval on the surface morphology vanishes in the case where the interval is larger than a certain value. Once atomic-steps are formed, further annealing has little influence on the terrace width. With proper parameters, repetition of the cycle of this technique, low temperature GS-MBE (LT-GS-MBE), gives rise to little change in the surface morphology. It is found that RTA is effective both for flattening the surface and for reducing the degree of dopant segregation under proper RTA condition.