Structural studies of crystalline and amorphous SiGe alloys using EXAFS and Raman scattering

Microstructural analysis of atomistic models of Si-rich amorphous silicon–germanium alloys

“…The comparison between our theoretical results and the experimental data of Chapman et al [3], shown in the insets of this figure, shows that the structural models with random distribution of Ge atoms reproduce well the measured coordination numbers Z Ge-Ge , contrary to the networks with Ge atom segregations. This allows us to conclude that the mixing of the Si and Ge atoms within the first-coordination shell in the Si-rich a-Si 1 − x Ge x :H films is random as expected [3,30,32]. The hypothesis of phase segregation on the nanometer scale in Si-rich amorphous silicon-germanium alloys is then discarded.…”

Hydrogenated microcrystalline silicon germanium: A bottom cell material for amorphous silicon-based tandem solar cells

“…The c-SiGe:H sample exhibits a weaker, shifted Si-Si peak from the crystallites due to the presence of nearby Ge. 9 A second, relatively sharp peak appears at ϳ400 cm Ϫ1 due to Si-Ge bonds in the crystallites, distinct from the broad peak at ϳ380 cm Ϫ1 observed in a-SiGe:H. served in this sample, appears at about 290 cm Ϫ1 with a broad shoulder towards lower frequencies. The 290 cm Ϫ1 peak can be ascribed to Ge-Ge bonds in the crystallites, shifted from the 300 cm Ϫ1 position in crystalline germanium due to the presence of nearby Si.…”

“…The 290 cm Ϫ1 peak can be ascribed to Ge-Ge bonds in the crystallites, shifted from the 300 cm Ϫ1 position in crystalline germanium due to the presence of nearby Si. 9 In Fig. 1͑b͒, the x-ray scattering intensities from the c-Si:H and c-SiGe:H samples are plotted as functions of 2.…”

Role of thermal annealing on SiGe thin films fabricated by PECVD

“…The peak centered at ∼260, ∼390 and ∼455 cm À 1 is attributed to Ge-Ge, Si-Ge and Si-Si transverse optic (TO) vibration modes, respectively. The Ge-Ge peak at ∼260 cm À 1 is shifted from the 300 cm À 1 position in crystalline germanium due to the presence of nearby Si [12]. The shift in SiGe peak to ∼390 cm À 1 from the standard at 400 cm À 1 depends on the amount of Ge content in the film and a monotonic shift of this peak with Ge content has been reported by Rath et al [13].…”