Laser crystallisation of silicon-germanium alloys

Scanning interference laser crystallisation is used to crystallize thin silicon, silicon-germanium and germanium layers. The initial films were deposited in an UHV chamber using an e-beam evaporator (Si) and an effusion cell (Ge). The laser crystallisation takes place in-situ to prevent contamination with oxidation during the laser crystallisation process. Crystallisation with a single pulse laser interference pattern causes the lateral grain growth towards the center of the interference lines. Lateral grain growth over the entire period of the interference pattern is observed for scanning laser interference crystallisation. Selective etching is applied to visualize the grain boundaries in the laser crystallized layers with Atomic Force Microscopy. The absorption coefficient of a series of Si, SiGe and Ge films is determined using Photothermal Deflection Spectroscopy. The conductance of a Si film prepared by this technique shows an anisotropic behaviour for directions parallel and perpendicular to the lateral growth direction. Specially resolved photocurrent experiments are applied to identify the grain size electrically.