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Structural and optical properties of germanium nanostructures on Si(100) and embedded in high-k oxides.

Ray SK, Das S, Singha RK, Manna S, Dhar A - Nanoscale Res Lett (2011)

Bottom Line: The structural and optical properties of Ge quantum dots (QDs) grown on Si(001) for mid-infrared photodetector and Ge nanocrystals embedded in oxide matrices for floating gate memory devices are presented.The temperature- and bias-dependent photocurrent spectra of a capped Si/SiGe/Si(001) QDs infrared photodetector device are presented.The properties of Ge nanocrystals of different size and density embedded in high-k matrices grown using radio frequency magnetron sputtering have been studied.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Meteorology, Indian Institute of Technology Kharagpur 721302, India. physkr@phy.iitkgp.ernet.in.

ABSTRACT
The structural and optical properties of Ge quantum dots (QDs) grown on Si(001) for mid-infrared photodetector and Ge nanocrystals embedded in oxide matrices for floating gate memory devices are presented. The infrared photoluminescence (PL) signal from Ge islands has been studied at a low temperature. The temperature- and bias-dependent photocurrent spectra of a capped Si/SiGe/Si(001) QDs infrared photodetector device are presented. The properties of Ge nanocrystals of different size and density embedded in high-k matrices grown using radio frequency magnetron sputtering have been studied. Transmission electron micrographs have revealed the formation of isolated spherical Ge nanocrystals in high-k oxide matrix of sizes ranging from 4 to 18 nm. Embedded nanocrystals in high band gap oxides have been found to act as discrete trapping sites for exchanging charge carriers with the conduction channel by direct tunneling that is desired for applications in floating gate memory devices.

No MeSH data available.


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The dark current density-voltage characteristics of a Ge QDIP structure measured at low temperatures.
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Figure 3: The dark current density-voltage characteristics of a Ge QDIP structure measured at low temperatures.

Mentions: The photo-response of Ge QD infrared photodetector (QDIP) has been studied at varying temperatures. Figure 3 shows the temperature-dependent dark current-voltage (J-V) characteristics of the QDIP device. The dark current density at 10 K is lower as compared to conventional infrared photo-detectors. The dark current density increases at elevated temperatures due to thermionic emissions. The fluctuations in J-V characteristic in both bias directions at 10 K are clearly observed, which reduces with increasing temperature and dies out at 40 K. This phenomenon is attributed to the carrier localization at the Si/Si1-xGex hetero-interface. These localized carriers result in an in-built voltage (Vb) varying from 0.2 to 0.32 V from 10 to 300 K. One origin of this carrier localization may be due to the confined holes and large valance band offset in Ge/Si heterostructure in type-II band alignment [14], which results in well for electrons at the Ge/Si interface in Si.


Structural and optical properties of germanium nanostructures on Si(100) and embedded in high-k oxides.

Ray SK, Das S, Singha RK, Manna S, Dhar A - Nanoscale Res Lett (2011)

The dark current density-voltage characteristics of a Ge QDIP structure measured at low temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211282&req=5

Figure 3: The dark current density-voltage characteristics of a Ge QDIP structure measured at low temperatures.
Mentions: The photo-response of Ge QD infrared photodetector (QDIP) has been studied at varying temperatures. Figure 3 shows the temperature-dependent dark current-voltage (J-V) characteristics of the QDIP device. The dark current density at 10 K is lower as compared to conventional infrared photo-detectors. The dark current density increases at elevated temperatures due to thermionic emissions. The fluctuations in J-V characteristic in both bias directions at 10 K are clearly observed, which reduces with increasing temperature and dies out at 40 K. This phenomenon is attributed to the carrier localization at the Si/Si1-xGex hetero-interface. These localized carriers result in an in-built voltage (Vb) varying from 0.2 to 0.32 V from 10 to 300 K. One origin of this carrier localization may be due to the confined holes and large valance band offset in Ge/Si heterostructure in type-II band alignment [14], which results in well for electrons at the Ge/Si interface in Si.

Bottom Line: The structural and optical properties of Ge quantum dots (QDs) grown on Si(001) for mid-infrared photodetector and Ge nanocrystals embedded in oxide matrices for floating gate memory devices are presented.The temperature- and bias-dependent photocurrent spectra of a capped Si/SiGe/Si(001) QDs infrared photodetector device are presented.The properties of Ge nanocrystals of different size and density embedded in high-k matrices grown using radio frequency magnetron sputtering have been studied.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Meteorology, Indian Institute of Technology Kharagpur 721302, India. physkr@phy.iitkgp.ernet.in.

ABSTRACT
The structural and optical properties of Ge quantum dots (QDs) grown on Si(001) for mid-infrared photodetector and Ge nanocrystals embedded in oxide matrices for floating gate memory devices are presented. The infrared photoluminescence (PL) signal from Ge islands has been studied at a low temperature. The temperature- and bias-dependent photocurrent spectra of a capped Si/SiGe/Si(001) QDs infrared photodetector device are presented. The properties of Ge nanocrystals of different size and density embedded in high-k matrices grown using radio frequency magnetron sputtering have been studied. Transmission electron micrographs have revealed the formation of isolated spherical Ge nanocrystals in high-k oxide matrix of sizes ranging from 4 to 18 nm. Embedded nanocrystals in high band gap oxides have been found to act as discrete trapping sites for exchanging charge carriers with the conduction channel by direct tunneling that is desired for applications in floating gate memory devices.

No MeSH data available.


Related in: MedlinePlus