Abstract: A method of forming a semiconductor-on-insulator device comprises the steps of forming a first alignment mark on a semiconductor substrate at a first reference position, forming a diffusion region in the semiconductor substrate at a position defined with respect to the first alignment mark according to a predetermined relationship, providing an insulator layer on the semiconductor substrate to expose a part of an upper major surface of the semiconductor substrate, providing a semiconductor layer on the insulator layer in contact with the exposed upper major surface of the semiconductor substrate, recrystallizing the semiconductor layer by heating up to a temperature above a melting point of the semiconductor layer and cooling down subsequently below the melting point, starting from a part of the semiconductor layer in contact with the exposed upper major surface of the semiconductor substrate and moving laterally along the semiconductor layer, to form a single crystal semiconductor layer having an upper major