Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 56: Optische Eigenschaften

HL 56.6: Talk

Friday, March 28, 2003, 13:00–13:15, POT/81

Optical properties of Ge implanted SiO₂ thin films — •Stefanie Hartmann¹, Steffen Knack¹, Alexander Milekhin², Johannes von Borany³, and Jörg Weber¹ — ¹Technische Universität Dresden — ²Novosibirsk State University — ³Forschungszentrum Rossendorf

We performed Raman and photoluminescence (PL) measurements on Ge implanted and rapid thermal annealed (RTA) SiO₂ layers on a (100) p-type Si substrate. The oxide layer thicknesses were 20 and 100 nm, respectively.

Raman measurements reveal a broad peak at approx. 300 cm⁻¹, which can be related to Ge-Ge vibrations and indicates the presence of (amorphous or crystalline) Ge clusters within the implanted oxide layer. Resonant Raman scattering at the Ge-rich layers showed a clear shift of the 300 cm⁻¹ Ge peak to lower wavelengths with increasing excitation energy, indicating the excitation of different cluster sizes. We tried to calculate the size distribution of the Ge clusters by using the measured FWHM of the 300 cm⁻¹ Ge peak.

The existence of crystalline Ge nanoclusters with sizes in the range of 2 - 5 nm was demonstrated by TEM micrographs.

PL measurements at 4.2 K and at room temperature showed neither the expected Ge cluster nor defect related luminescence. At 4.2 K a characteristic emission band in the infrared could be observed (No-dqWNo-dq or No-dqI1No-dq line at 1018.2 meV), which is related to ion implantation damage in the Si substrate. This defect luminescence could be annealed out at temperatures above 950 ^∘C during the RTA process.