Morphology of Si1−xGex thin crystalline films obtained by pulsed-excimer-laser annealing of heavily Ge-implanted Si

Thin crystalline Si1−xGex films have been obtained by irradiating heavily (∼ 1.5 × 1017 ions/cm2) Ge-implanted <100> Si with a pulsed ArF excimer laser. The crystallization of the layer amorphized by implantation occurs by a melting-solidification process during and after the laser pulse. The influences of implantation conditions of laser energy density or number of laser pulses on the layer configuration (crystallinity and grain size) are observed by transmission electron microscopy on cross-sections and by grazing X-ray diffraction. The beam energy for implantations ranged from 50 to 150 keV and the laser energy density from 0.9 to 1.2 J cm2. Structures obtained after complete as well as incomplete melting of the whole amorphized layer have been investigated. For example: a monocrystalline layer can be observed (implantation: 100 keV; laser: 0.9 J/cm2, 20 pulses) or successive polycrystalline layers: large grains of Si1−xGex near the surface on poly-Si (implantation: 80 keV up to 8 × 1016 atoms/cm2 then 50 keV up to 1017 atoms/cm2; laser: 1.2 J/cm2, 10 pulses). The observations also show the grain growth induced by increasing number of pulses.