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10 × 10 μm2 AFM images of Si0.098Ge0.844Sn0.058 sample with different post-growth annealing. (a) As-grown surface roughness RMS = 0.59 nm, (b) 30 s RTA at 500 °C, RMS = 1.04 nm and (c) 120 s RTA at 500 °C, RMS = 1.18 nm.
TEM cross section image of Si0.098Ge0.844Sn0.058 sample after 120 s RTA at 500 °C. No visible precipitates or threading dislocations are seen.
Room-temperature PR spectra of unstrained SixGe1−x−ySny samples with fixed Sn/Ge ratio about 0.069, but different Si concentrations: (i) Si = 0%, (ii) Si = 5.5%, (iii) Si = 9.8%. The solid red lines are fitting curves for PR spectra. Sample (i) is as grown sample and samples (ii) and (iii) are annealed for 120 s at 500 °C, while the dashed blue curve inside (ii) represents the same sample after 30 s RTA at 500 °C.
The bandgap energy of SixGe1−x−ySny alloys as function of Si concentration. (a) Fixed ratio of Sn/Ge ≈ 0.069. (b) Different fixed lattice constants: a ≈ 5.716 Å for green dashed-dotted line; a ≈ 5.699 Å for red dashed line; a ≈ 5.687 Å for black solid line.
The difference energy E as function of xy of SixGe1−x−ySny alloys with a linear fit. The slope of the line is −21 ± 4 eV.
Measured SixGe1−x−ySny compositions, lattice constants, and direct bandgap energies. The compositions of Ge1−zSnz samples were determined by XRD.12
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