Preferential Growth of Al (110) Films on GaAs (100) Surfaces under Rapid Vapor Deposition in Ordinary High Vacuum

In order to confirm the effect of the rapid evaporation during film growth, 100 nm thick Al films were deposited from dual sources of W baskets onto (100) surfaces of GaAs substrates heated at a temperature of 473 to 723 K in an ordinary high vacuum (10−3 Pa). From a transmission electron microscopic examination of the films, it was found that the optimum substrate temperature was 673 K for the growth of a (110) epitaxial film; the obtained film was mostly composed of islands with the orientation relationship of (110)[001]Al//(100)[011]GaAs. During the early stage of deposition, however, numerous islands grew in various crystallographic orientations on the substrate heated at 673 K; the epitaxy was found in the films thicknesses greater than 80 nm.