Abstract
Optical properties of dislocations free state-of-the-art Germanium(Ge) and Germanium-on-insulator(GeOI) wafers have been characterized using Fourier transformed infrared spectroscopy at oblique incidence, attenuated total reflectance, laser Raman scattering and optical transmission at room temperature. In n-type Ge, in addition to vibrational modes observed in intrinsic(i) Ge, a band at 535 cm-1, 668 cm-1 and a strong peak at 1590 cm-1 were observed. At oblique incidence, the bands at high energies loose their intensity and those at 500-600 cm-1 become stronger and new bands appear at 840 and 945 cm-1. Thermal annealing reveals the precipitation of GeO as evidenced from the band structure at 845 cm-1 and an absorption dip at 808 cm-1 in p-type Ge. The appearance of new bands and the change in band strengths are in general observed in both type of wafers at oblique incidence. GeOI exhibits a strong disorder induced longitudinal optic (LO)-TO coupling mode which can only be observed at non-normal incidence. Optical absorption at the near band edge reveals the presence of doping related disorder and band shrinkage, which is supported also by Ge-Ge one-phonon line broadening at 301 cm-1.
Original language | English |
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Pages (from-to) | 753-758 |
Number of pages | 6 |
Journal | Materials Science in Semiconductor Processing |
Volume | 9 |
Issue number | 4-5 SPEC. ISS. |
DOIs | |
Publication status | Published - Aug 2006 |
Externally published | Yes |
Keywords
- Germanium (Ge)
- Germanium-on-insulator (GeOI)