Grain size dependence in a self-implanted silicon layer on laser irradiation energy density

The transformation of amorphous Si layers to polycrystalline material induced by Q-switched ruby laser single pulses of 20 and 50 nsec duration has been investigated. The analysis has been performed by transmission electron microscopy and by channeling measurements using 2.0-MeV He+ Rutherford backscattering. The average grain size of the polycrystalline layers increases with the incident energy density of the laser pulse in the range 0.6–1.7 J/cm2. A transition to single-crystal layers is found for incident energy densities around 2.0 J/cm2. The grain size correlates with incident energy density (J/cm2) rather than incident power density (MW/cm2) for these pulse durations.