In the presence of a dense ([MATH] 1021/cm3) electron-hole plasma which may be produced by the intense irradiation during pulsed laser annealing, the covalent bonding of tetrahedral semiconductors like Si will be severely weakened because a significant fraction of the bond charge has been excited across the gap into antibonding or plane wave States. The crystal structure may even become unstable and undergo a phase transition if the bond charge is reduced beyond a critical point where the transverse acoustic modes go to zero frequency. This transition has previously been estimated from the temperature dependence of the gap to occur at a density of 8×1021/cm3 for a lattice temperature of 0 K and at lower densities for higher lattice temperatures. In this state the material would not be able to support a shear and so should be called a liquid, but it would be very distinct from molten Si. The energy from the laser would be concentrated in the electronic excitation and not in kinetic energy of the atoms, as in the thermal case. Recrystallization could occur without the destructive effects of severe thermal gradients when the material passes back through this phase transition to the covalently bonded phase. However, recrystallization of ion-implanted material should also be possible without passing through this phase transition if the atoms are reordered by the optically induced gliding of dislocations out of the damaged zone, as has been observed in crystalline semiconductors. Point defects should be removed from amorphous or damaged material at a rate much greater than normal furnace annealing due to five separate effects. First, they may be eliminated by recrystallization following the phase transition. Second, they may experience recombination enhanced diffusion within the covalent phase. Third, the coulombic trapping by charged impurities, which normally reduces the net rate of vacancy (or interstitial) migration drastically, will be suppressed by the flux of free carriers in the dense plasma. Fourth, point defects may be swept out of the material as the large concentration of dislocations, which are ideal sinks, glide out. Fifth, the energy of formation of fast diffusing interstitial species can be greatly reduced by the dense plasma. It is claimed that these effects are required to account for the very high crystallographic, morphological and electrical quality of Si produced by pulsed laser annealing