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Electromodulated reflectance study of self-assembled Ge/Si quantum dots.

Yakimov A, Nikiforov A, Bloshkin A, Dvurechenskii A - Nanoscale Res Lett (2011)

Bottom Line: Up to three optical transitions are observed.The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band.The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. yakimov@isp.nsc.ru.

ABSTRACT
We perform an electroreflectance spectroscopy of Ge/Si self-assembled quantum dots in the near-infrared and in the mid-infrared spectral range. Up to three optical transitions are observed. The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band. The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.

No MeSH data available.


PC spectra of the QD and WL structures measured in a short circuit configuration at T = 95 K.
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Figure 2: PC spectra of the QD and WL structures measured in a short circuit configuration at T = 95 K.

Mentions: First we checked the photocurrent (PC) response from the devices under investigation. The applied bias was 0 V and the PC was measured in a short circuit configuration. A 2-mm-thick Si wafer serving as a filter was introduced to remove the strong PC signal due to the band-to-band transitions in the Si epitaxial layers for energies larger than 1.1 eV. Below the Si band gap energy, there is only a weak PC signal for the sample with Ge WLs (Figure 2). The spectral response of the device with QDs clearly covers a broader spectral range extending down to a half of eV.


Electromodulated reflectance study of self-assembled Ge/Si quantum dots.

Yakimov A, Nikiforov A, Bloshkin A, Dvurechenskii A - Nanoscale Res Lett (2011)

PC spectra of the QD and WL structures measured in a short circuit configuration at T = 95 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211264&req=5

Figure 2: PC spectra of the QD and WL structures measured in a short circuit configuration at T = 95 K.
Mentions: First we checked the photocurrent (PC) response from the devices under investigation. The applied bias was 0 V and the PC was measured in a short circuit configuration. A 2-mm-thick Si wafer serving as a filter was introduced to remove the strong PC signal due to the band-to-band transitions in the Si epitaxial layers for energies larger than 1.1 eV. Below the Si band gap energy, there is only a weak PC signal for the sample with Ge WLs (Figure 2). The spectral response of the device with QDs clearly covers a broader spectral range extending down to a half of eV.

Bottom Line: Up to three optical transitions are observed.The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band.The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. yakimov@isp.nsc.ru.

ABSTRACT
We perform an electroreflectance spectroscopy of Ge/Si self-assembled quantum dots in the near-infrared and in the mid-infrared spectral range. Up to three optical transitions are observed. The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band. The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.

No MeSH data available.