Method and apparatus for producing semiconductor layers composed of amorphous silicon-germanium alloys through glow discharge technique, particularly for solar cells

A method and apparatus are provided for improving the dangling-bond saturation in amorphous silicon-germanium semiconductor layers. The deposition from the vapor phase of germane, silane, and hydrogen proceeds on the basis of different plasma excitations in the same reactor, that are spatially separated. Capacitive and inductively coupled plasmas are generated at different locations, in such a manner that the two plasmas superimpose in a central substrate region. For increasing the ionization density, the inductively excited plasma has a dc magnetic field for resonance excitation superimposed on it perpendicular to the radio frequency magnetic field. Amorphous silicon-germanium layers containing hydrogen are produced that have a low density of states and are particularly suitable for thin-film tandem solar cells.