Phase-correct bond lengths in crystallineGexSi1−xalloys

EXAFS study on poly-Si1−XGeX films prepared by reactive thermal CVD method

“…It is considered that the Ge atoms tend to isolate in the alloy matrix. The bond length of GeGe is larger than in the results of previous studies [7][8][9][10] for the MBE Si 1ÀX Ge X films. This indicates the Ge-Ge bonds are mainly located near the substrate interface region where the Ge fraction is high.…”

“…3. Since, in the high x region, the value of r G tends to approach the covalent bond length of the Ge-Ge pair, 2.450 Å , the values of r G of the reactive thermal CVD in the present study are larger than those in the results from the previous studies [7][8][9][10]. The origin of the high Ge fraction region near the substrate interface should be investigated in further studies on thinner Si 1ÀX Ge X films.…”

“…This indicates the Ge-Ge bonds are mainly located near the substrate interface region where the Ge fraction is high. The Ge-Si bond lengths of reactive thermal CVD are smaller than those found in previous studies [7][8][9][10]. It is considered that the Ge atoms tend to isolate in the Si matrix in the reactive thermal CVD Si 1ÀX Ge X films and that the Ge-Si bond length is shortened by the confinement of the Si matrix network.…”

“…7. In this figure, the previous study results [7][8][9][10] are also illustrated. The dashed lines are the predicted x dependence of the bond lengths within the topological rigidity model for a ** value of 0.70 [7].…”

“…Ge K-edge EXAFS analyses were carried out on several Si 1ÀX Ge X films of different thicknesses fabricated using an identical deposition condition. Structural changes during the deposition, as well as the structural features of the reactive thermal CVD Si 1ÀX Ge X , are discussed compared to previous EXAFS studies [7][8][9][10] on this alloy system.…”