DEPENDENCE OF MICROCRYSTAL SIZE ON HYDROGEN GAS-PRESSURE IN SILICON-BASED ALLOYS PREPARED BY REACTIVE LASER ABLATION

The silicon-based alloys have been fabricated by means of an excimer laser (XeCl; 308 nm) ablation in a pure hydrogen atmosphere for the first time, and their crystallographic structure has been investigated by an x-ray diffraction method, as a function of hydrogen gas pressure P(H2) (0.1-3.0 Torr) during the deposition. As a result, it is found that the alloys prepared at both about 100 and 300 K contain silicon microcrystals, and their size becomes a minimum at P(H2) congruent-to 0.5 Torr. On the other hand, the lattice constant increases monotonically with increasing hydrogen gas pressure in the range of 0.1 Torr less-than-or-equal-to P(H2) less-than-or-equal-to 3.0 Torr. The results are discussed in relation to the growth mechanism.