The present invention proposes variations of the
laser separation method allowing separating homoepitaxial films from the substrates made from the same crystalline material as the epitaxial film. This new method of
laser separation is based on using the selective
doping of the substrate and epitaxial film with fine donor and
acceptor impurities. In selective
doping,, concentration of free carries in the epitaxial film and substrate may essentially differ and this can lead to strong difference between the light absorption factors in the
infrared region near the residual beams region where free carriers and
phonon-
plasmon interaction of the optical phonons with free carriers make an essential contribution to
infrared absorption of the optical phonons. With the appropriate selection of the
doping levels and frequency of
infrared laser radiation it is possible to achieve that laser
radiation is absorbed in general in the region of strong doping near the interface substrate- homoepitaxial film. When scanning the interface substrate- homoepitaxial film with the focused laser beam of sufficient power,
thermal decomposition of the
semiconductor crystal takes place with subsequent separation of the homoepitaxial film. The
advantage of the proposed variations of the method for laser separation of epitaxial films in comparison with the known ones is in that it allows to separate homoepitaxial films from the substrates, i.e., homoepitaxial films having the same width of the forbidden gap as the initial
semiconductor substrate has. The proposed variations of the method can be used for separation of the epitaxial films. Besides, the proposed method allows using the high-effective and inexpensive infrared gas
silicon dioxide CO2 or
silicon oxide CO lasers for separation of the epitaxial films.