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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.


Related in: MedlinePlus

Typical AFM topographic images for (a) 2 min (sample 'GS-1') and (b) 5 min (sample 'GS-2') grown Ge islands deposited at a substrate temperature 500°C.
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Figure 1: Typical AFM topographic images for (a) 2 min (sample 'GS-1') and (b) 5 min (sample 'GS-2') grown Ge islands deposited at a substrate temperature 500°C.

Mentions: Figure 1a, b shows the AFM images of the MBE grown Ge islands deposited for 2 (sample 'GS-1') and 5 min (sample 'GS-2'), respectively, at a substrate temperature of 500°C. From AFM topographic images, the variation of island shape, size, and density is clearly visible. A bimodal size distribution of islands is visible from Figure 1a. The average diameter (L), height (h) for larger and smaller islands are L = 54 nm, h ~ 18 nm and L = 23 nm, h = 7 nm, respectively, for sample 'GS-1'. On the other hand, the growth of multifaceted dome like structure is evident in Figure 1b for the 'GS-2' sample with the average islands size L = 90 nm and h = 35 nm. In Stranski-Krastanov (S-K) growth of above islands, the arrangement of deposited Ge atoms begins with the formation of a strained planar layer called the wetting layer (WL), until a critical thickness is reached. A further increase of the deposited material leads to the nucleation of three-dimensional Ge islands on the wetting layer. At the first stage of the growth, the islands are square-based pyramids [11,12]. Upon collecting more adatoms by the process of coarsening (Ostwald ripening) from neighboring islands, these pyramids transform to strained multifaceted domes. From Figure 1b it is seen that for longer time Ge deposition, the smaller islands coalesce to form multifaceted domes. One can also change the islands size and shape distribution by post-growth annealing [13].


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)

Typical AFM topographic images for (a) 2 min (sample 'GS-1') and (b) 5 min (sample 'GS-2') grown Ge islands deposited at a substrate temperature 500°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Typical AFM topographic images for (a) 2 min (sample 'GS-1') and (b) 5 min (sample 'GS-2') grown Ge islands deposited at a substrate temperature 500°C.
Mentions: Figure 1a, b shows the AFM images of the MBE grown Ge islands deposited for 2 (sample 'GS-1') and 5 min (sample 'GS-2'), respectively, at a substrate temperature of 500°C. From AFM topographic images, the variation of island shape, size, and density is clearly visible. A bimodal size distribution of islands is visible from Figure 1a. The average diameter (L), height (h) for larger and smaller islands are L = 54 nm, h ~ 18 nm and L = 23 nm, h = 7 nm, respectively, for sample 'GS-1'. On the other hand, the growth of multifaceted dome like structure is evident in Figure 1b for the 'GS-2' sample with the average islands size L = 90 nm and h = 35 nm. In Stranski-Krastanov (S-K) growth of above islands, the arrangement of deposited Ge atoms begins with the formation of a strained planar layer called the wetting layer (WL), until a critical thickness is reached. A further increase of the deposited material leads to the nucleation of three-dimensional Ge islands on the wetting layer. At the first stage of the growth, the islands are square-based pyramids [11,12]. Upon collecting more adatoms by the process of coarsening (Ostwald ripening) from neighboring islands, these pyramids transform to strained multifaceted domes. From Figure 1b it is seen that for longer time Ge deposition, the smaller islands coalesce to form multifaceted domes. One can also change the islands size and shape distribution by post-growth annealing [13].

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