Morphology of epitaxial SrF2 films on atomically modified InP(100)

This paper presents the first results of our molecular beam epitaxy (MBE) experiments on the growth of SrF2 on InP(100) using synchrotron radiation photoelectron spectroscopy (SRPES). Two different ways of preparing the InP surface were used: ex situ HF etching and in situ As treatment. Whereas HF etching provided a clean but rough surface, As treatment led to a flat InP surface with a two-monolayer thick InAs overlayer. The SrF2 grew epitaxially even at room temperature (RT). There was a significant difference in surface roughness of 50 Å thick films grown on these two InP surfaces at RT and then annealed at 500°C for 10 min. The film deposited on the HF etched InP surface had a roughness of 1.8 Å, which is rather flat, whereas the film deposited on the As-treated surface had a roughness of 4.5 Å, which is rather rough. These roughnesses were determined by atomic force microscopy (AFM). A possible growth model is discussed.