STUDY OF EPITAXIAL-GROWTH OF ROTATIONAL-TWIN-FREE CAF2 FILMS ON SI(111)

It was shown that the 2-step growth method is very effective for growing rotational-twin-free CaF2 filMS On Si(111) which is called type-A. Experimental study of the eff ect of thickness of the first layer in the 2-step growth method revealed the thickness of a first grown layer more than about 8 monolayers (ML) was necessary to obtain uniform type-A CaF2 films, and that mixed or uniform type-B CaF2 if it is less than 4 ML. A growth model in which the 1st layer must be rotated around the normal axis of Si(111) during the substrate temperature elevation just before the 2nd step growth if the lst layer is less than 4 ML is proposed.