We have studied the early stage and successive stage of the growth of poly-Si(1-x)Ge(x) films in gas-source molecular beam deposition (GSMBD), in which disilane and germane are utilized as source gases. Solid-source molecular beam deposition (SSMBD) was also used for the film formation in comparison with GSMBD. In GSMBD, the grain size is larger than that in SSMBD in the early stage of the growth and the grains after growth have columnar structures. In SSMBD, there are many small grains in the early stage of the growth, and the successive growth formed grains with the shape of triangular pyramid. (c) 2008 Elsevier B.V. All rights reserved