Schematic of the strained Si/SiGe layer structure.
SIMS profile showing the measured variation in Ge concentration with depth through the structure.
Profilometer image of the bevelled sample. The sharp bevel angle is evident.
Raman spectra (acquired with visible laser) showing the impact of tensile and compressive strains on the pure Si peak position. The impact of strain and Ge content on the peak position of a SiGe alloy is also shown.
Median value of strain along the linescan and variation in strain (calculated as the standard deviation/median strain value from each linescan) for the unbevelled sample and the polished and unpolished surfaces of the bevelled sample. Both samples are from the same wafer. The measurements were carried out using a visible laser.
Raman spectra obtained using an UV laser showing the intensity transition between the strained Si and SiGe peaks at three different positions along the bevelled surface.
Variation in tensile strain and SiGe peak position along the bevel line scan. Lateral periodic variations in SiGe peak position originate in the compositionally graded SiGe layer and are transferred to the Si film (on the unbevelled side).
AFM image showing the cross-hatch morphology of the sample. The undulations are related to periodic fluctuations of strain fields in the SiGe virtual substrate.
Strain profile through the tensile strained Si layer. The strained Si channel thickness inferred from the Raman data is 17 nm, in precise agreement with SIMS data (Fig. 2). The Ge concentration is determined to be 16%, showing a 1% discrepancy with XRD and 4% discrepancy from SIMS.
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