Controlled line shaped electron beam for silicon zone melting recrystallization on float glass substrates

A line shaped electron beam system for the zone melting recrystallization (ZMR) of thick silicon films on float glass substrates is described. The low thermal stability of the glass requires a rapid regulated zone heating. The electron beam system allows the ZMR in a continuous scan without pulsing. The setup consists of the tungsten wire with a Pierce reflector as line cathode and the moving substrate as anode. A negative voltage applied on the reflectors limits the electron emission and provides the necessary control. The melt energy for optimized processing decreases with an increase of the velocity. The beam profiles and penetration depth of the electrons is discussed. Homogenous polycrystalline silicon areas of several 10cm2 are achieved on a tungsten coated borosilicate float glass for the intended use as solar cell absorber.