Patent ID: 8598051

Claim:
A system for fabricating a radiation-absorbing semiconductor substrate, comprising: a processing chamber having an inlet port for introducing a gas into the chamber, a movable substrate holder disposed in said chamber and configured for holding a semiconductor substrate, a motion controller coupled to said substrate holder for moving the holder, a window coupled to the chamber for allowing passage of radiation into the chamber for processing said semiconductor substrate, a laser radiation source for generating laser pulses, said source being optically coupled to said window such that the laser pulses impinge on a surface of the semiconductor substrate, a lens for focusing said laser radiation pulses onto the semiconductor substrate surface, a camera positioned outside the chamber, a mirror configured to redirect the laser radiation after its passage through the lens onto the camera when the mirror is positioned in the path of the laser radiation, wherein said camera is positioned at a distance from the lens that is substantially equal to a distance of the lens from the substrate surface, thereby providing a measure of a spotsize of the radiation pulses on the substrate surface, and wherein said controller is capable of moving the substrate while the surface of the substrate is irradiated by said radiation pulses in presence of the gas in the chamber.