Calorimetric studies of crystallization and relaxation of amorphous Si and Ge prepared by ion implantation.

Amorphous Si and Ge layers, produced by noble gas (Ar or Xe) implantation of single crystal substrates, have been crystallized in a differential scanning calorimeter (DSC). The MeV implantation energies resulted in amorphous layers of micron thickness whose areal densities were determined using the Rutherford Backscattering and channeling of 1 MeV protons. These techniques allow determination of the amorphous-crystal interface velocity (which is proportional to the rate of heat evolution, deltaH(ac)(dot)), and the total enthalpy of crystallization deltaH(ac). Amorphous Ge was found to relax continuously to an amorphous state of lower free energy, with a total enthalpy of relaxation of 6.0kJ/mole before the onset of rapid crystallization.