INITIAL-STAGES OF THE GROWTH OF SRF2 ON INP

In this paper we present very detailed results of our experiments on the deposition of SrF2 on InP. Four different substrates were used for these investigations: HF-etched and As-treated InP(100) and (111). On these surfaces, 35-50 Angstrom of SrF2 was deposited at room temperature. We also studied the changes in the films due to annealing. Very surface-sensitive synchrotron radiation photoelectron spectroscopy was employed to obtain information about the morphology of the films as well as the chemical bonding between the constituents. To further clarify the morphology, several other methods were used as well. On HF-etched InP(100) the SrF2 grows as a flat polycrystalline film. The film deposited on HF-etched InP(111) is also flat, but its crystallinity is better. A texture is found for this film. On the other hand, on As-treated InP the SrF2 grows with a rough surface. On As-treated InP(100) the SrF2 grows in the Stranski-Krastanov mode. The thickness of the continuous base layer is two monolayers. On As-treated InP(111) the SrF2 grows as a continuous film, but with a large surface roughness. Only for the HF-etched InP(111) substrate is an interfacial reaction found after annealing the film at 500 degrees C for 10 min indicating a strong chemical bonding between the film and the substrate.