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The structural and optical properties of GaSb/InGaAs type-II quantum dots grown on InP (100) substrate.

Shuhui Z, Lu W, Zhenwu S, Yanxiang C, Haitao T, Huaiju G, Haiqiang J, Wenxin W, Hong C, Liancheng Z - Nanoscale Res Lett (2012)

Bottom Line: Rectangular-shaped GaSb QDs were well developed and no nanodash-like structures which could be easily found in the InAs/InP QD system were formed.Low-temperature photoluminescence spectra show there are two peaks centered at 0.75eV and 0.76ev.This material system shows a promising application on quantum-dot infrared detectors and quantum-dot field-effect transistor.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China. lwang@iphy.ac.cn.

ABSTRACT
We have investigated the structural and optical properties of type-II GaSb/InGaAs quantum dots [QDs] grown on InP (100) substrate by molecular beam epitaxy. Rectangular-shaped GaSb QDs were well developed and no nanodash-like structures which could be easily found in the InAs/InP QD system were formed. Low-temperature photoluminescence spectra show there are two peaks centered at 0.75eV and 0.76ev. The low-energy peak blueshifted with increasing excitation power is identified as the indirect transition from the InGaAs conduction band to the GaSb hole level (type-II), and the high-energy peak is identified as the direct transition (type-I) of GaSb QDs. This material system shows a promising application on quantum-dot infrared detectors and quantum-dot field-effect transistor.

No MeSH data available.


AFM and STEM images of GaSb/In0.53Ga0.47As QDs and histogram of the height of GaSb/In0.53Ga0.47As QDs. (a) The AFM image of GaSb/In0.53Ga0.47As QDs, (b) histogram of the height of GaSb/In0.53Ga0.47As QDs, and (c) the STEM image of GaSb/In0.53Ga0.47As QDs.
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Figure 1: AFM and STEM images of GaSb/In0.53Ga0.47As QDs and histogram of the height of GaSb/In0.53Ga0.47As QDs. (a) The AFM image of GaSb/In0.53Ga0.47As QDs, (b) histogram of the height of GaSb/In0.53Ga0.47As QDs, and (c) the STEM image of GaSb/In0.53Ga0.47As QDs.

Mentions: In order to characterize the density, shape, diameter, and height size distribution of GaSb/InGaAs QDs on InP (100) substrate, the AFM and STEM measurements were carried out. Figure 1 shows the AFM and STEM images of GaSb/In0.53Ga0.47As QDs and the histogram of the height of GaSb/In0.53Ga0.47As QDs. As shown in Figure 1a, the statistical data indicate that the density of the QDs is approximately 7 × 109 cm-2 and that the shape of GaSb QDs is rectangular-shaped which is the same with GaSb/GaAs QDs [9]. Figure 1b shows the height distribution of the GaSb/In0.53Ga0.47As QDs. From the figure, we can see that the height of the quantum dots is mainly concentrated to approximately 6 nm. Due to the well known 'tip effect' of AFM, the results of AFM measurements cannot describe the precise lateral size of the QDs. The STEM measurements were used to image the configuration for overcoming this limitation of AFM measurements. Figure 1c shows that the lateral size of the QDs is approximately 40 nm. The results indicate that the rectangular-shaped GaSb/InGaAs QDs are well developed in the SK growth mode, but no nanodash-like structures which are easily found in the InAs/InP QD system were formed [19]. However, there seemed to be some smaller QDs (the lateral size was about 20 nm) in the AFM image. By measuring the height distribution of the QDs, we observed that they were lower than 2 nm. We did not observe such bimodal distribution in the STEM images. So, we thought that these mound-like structures were possibly from the non-optimized InGaAs buffer layer. Another possible explanation was that the formation of the InGaAsSb wetting layer resulted in the accumulation of individual atoms on the surface to form a mound-like structure, due to the intermixing of As and Sb during the growth of GaSb QD.


The structural and optical properties of GaSb/InGaAs type-II quantum dots grown on InP (100) substrate.

Shuhui Z, Lu W, Zhenwu S, Yanxiang C, Haitao T, Huaiju G, Haiqiang J, Wenxin W, Hong C, Liancheng Z - Nanoscale Res Lett (2012)

AFM and STEM images of GaSb/In0.53Ga0.47As QDs and histogram of the height of GaSb/In0.53Ga0.47As QDs. (a) The AFM image of GaSb/In0.53Ga0.47As QDs, (b) histogram of the height of GaSb/In0.53Ga0.47As QDs, and (c) the STEM image of GaSb/In0.53Ga0.47As QDs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 1: AFM and STEM images of GaSb/In0.53Ga0.47As QDs and histogram of the height of GaSb/In0.53Ga0.47As QDs. (a) The AFM image of GaSb/In0.53Ga0.47As QDs, (b) histogram of the height of GaSb/In0.53Ga0.47As QDs, and (c) the STEM image of GaSb/In0.53Ga0.47As QDs.
Mentions: In order to characterize the density, shape, diameter, and height size distribution of GaSb/InGaAs QDs on InP (100) substrate, the AFM and STEM measurements were carried out. Figure 1 shows the AFM and STEM images of GaSb/In0.53Ga0.47As QDs and the histogram of the height of GaSb/In0.53Ga0.47As QDs. As shown in Figure 1a, the statistical data indicate that the density of the QDs is approximately 7 × 109 cm-2 and that the shape of GaSb QDs is rectangular-shaped which is the same with GaSb/GaAs QDs [9]. Figure 1b shows the height distribution of the GaSb/In0.53Ga0.47As QDs. From the figure, we can see that the height of the quantum dots is mainly concentrated to approximately 6 nm. Due to the well known 'tip effect' of AFM, the results of AFM measurements cannot describe the precise lateral size of the QDs. The STEM measurements were used to image the configuration for overcoming this limitation of AFM measurements. Figure 1c shows that the lateral size of the QDs is approximately 40 nm. The results indicate that the rectangular-shaped GaSb/InGaAs QDs are well developed in the SK growth mode, but no nanodash-like structures which are easily found in the InAs/InP QD system were formed [19]. However, there seemed to be some smaller QDs (the lateral size was about 20 nm) in the AFM image. By measuring the height distribution of the QDs, we observed that they were lower than 2 nm. We did not observe such bimodal distribution in the STEM images. So, we thought that these mound-like structures were possibly from the non-optimized InGaAs buffer layer. Another possible explanation was that the formation of the InGaAsSb wetting layer resulted in the accumulation of individual atoms on the surface to form a mound-like structure, due to the intermixing of As and Sb during the growth of GaSb QD.

Bottom Line: Rectangular-shaped GaSb QDs were well developed and no nanodash-like structures which could be easily found in the InAs/InP QD system were formed.Low-temperature photoluminescence spectra show there are two peaks centered at 0.75eV and 0.76ev.This material system shows a promising application on quantum-dot infrared detectors and quantum-dot field-effect transistor.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China. lwang@iphy.ac.cn.

ABSTRACT
We have investigated the structural and optical properties of type-II GaSb/InGaAs quantum dots [QDs] grown on InP (100) substrate by molecular beam epitaxy. Rectangular-shaped GaSb QDs were well developed and no nanodash-like structures which could be easily found in the InAs/InP QD system were formed. Low-temperature photoluminescence spectra show there are two peaks centered at 0.75eV and 0.76ev. The low-energy peak blueshifted with increasing excitation power is identified as the indirect transition from the InGaAs conduction band to the GaSb hole level (type-II), and the high-energy peak is identified as the direct transition (type-I) of GaSb QDs. This material system shows a promising application on quantum-dot infrared detectors and quantum-dot field-effect transistor.

No MeSH data available.