STRUCTURAL CHARACTERIZATION OF AMORPHOUS SILICON AND GERMANIUM.

We have derived a simple relationship between the measured TO-phonon frequency and the square of the TO-phonon Raman linewidth. The minimum strain energy calculated from the minimum DELTA theta prior to crystallization compares favorably with the enthalpy of crystallization, being 15 KJ/mole for a-Si and 9. 4 KJ/mole for a-Ge. The variation of DELTA theta with T//a may be fitted to an activated process resulting in an energy barrier of approximately 0. 19 ev and 0. 18 ev for a-Si and a-Ge, respectively. We have also derived an expression allowing the determination of DELTA theta from optical absorption, thereby opening the door for many investigators regarding a quantitative measure of DELTA theta . Since DELTA theta affects the distance between the second nearest neighbors, the minimum hydrogen content for strain relieving is 6%, although it is more probable that 12% is required if two hydrogen atoms are bonded to two adjacent atoms.