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 growi ng 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 t he 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 tha n 4 ML. A growth model in which the 1st layer must be rotated around t he normal axis of Si(111) during the substrate temperature elevation j ust before the 2nd step growth if the lst layer is less than 4 ML is p roposed.