A method for forming a structure, the method comprising the steps of: providing a crystalline semiconductor substrate comprising a first semiconductor material and having a top surface; forming a mask over a top surface of the crystalline semiconductor substrate, and defining a mask opening in the mask to expose a portion of the top surface of the crystalline semiconductor substrate; performing a selective etch to expose a specific crystal plane of the crystalline semiconductor substrate in a bottom portion of the mask opening; removing the mask; defining a non-crystalline layer over the crystalline semiconductor substrate obtained in the previous steps; defining an opening formed in the non-crystalline layer, having a non-crystalline sidewall and being formed by a selective removal process, so that the opening terminates at the top surface of the crystalline semiconductor substrate to reveal the previously exposed specific crystal plane and so that the non-crystalline sidewall of the opening defines an angle of less than 90° with the exposed crystal plane; forming an epitaxial film in the opening, the epitaxial film comprising a second semiconductor material and including a growth front, the growth front including a surface comprising a facet, not parallel to the top surface, and the surface defining approximately the same angle with the non-crystalline sidewall of the opening, the second semiconductor material being lattice-mismatched to the first semiconductor material, wherein dislocations in the epitaxial film are directed in a direction substantially perpendicular to the growth front, so that the dislocations are trapped by the non-crystalline sidewall of the opening. providing a crystalline semiconductor substrate comprising a first semiconductor material and having a top surface; forming a mask over a top surface of the crystalline semiconductor substrate, and defining a mask opening in the mask to expose a portion of the top surface of the crystalline semiconductor substrate; performing a selective etch to expose a specific crystal plane of the crystalline semiconductor substrate in a bottom portion of the mask opening; removing the mask; defining a non-crystalline layer over the crystalline semiconductor substrate obtained in the previous steps; defining an opening formed in the non-crystalline layer, having a non-crystalline sidewall and being formed by a selective removal process, so that the opening terminates at the top surface of the crystalline semiconductor substrate to reveal the previously exposed specific crystal plane and so that the non-crystalline sidewall of the opening defines an angle of less than 90° with the exposed crystal plane; forming an epitaxial film in the opening, the epitaxial film comprising a second semiconductor material and including a growth front, the growth front including a surface comprising a facet, not parallel to the top surface, and the surface defining approximately the same angle with the non-crystalline sidewall of the opening, the second semiconductor material being lattice-mismatched to the first semiconductor material, wherein dislocations in the epitaxial film are directed in a direction substantially perpendicular to the growth front, so that the dislocations are trapped by the non-crystalline sidewall of the opening.