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Nanoscale optical positioning of single quantum dots for bright and pure single-photon emission.

Sapienza L, Davanço M, Badolato A, Srinivasan K - Nat Commun (2015)

Bottom Line: Self-assembled, epitaxially grown InAs/GaAs quantum dots (QDs) are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications.However, self-assembled growth results in an essentially random in-plane spatial distribution of QDs, presenting a challenge in creating devices that exploit the strong interaction of single QDs with highly confined optical modes.Here, we present a photoluminescence imaging approach for locating single QDs with respect to alignment features with an average position uncertainty <30 nm (<10 nm when using a solid-immersion lens), which represents an enabling technology for the creation of optimized single QD devices.

View Article: PubMed Central - PubMed

Affiliation: 1] Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA [2] Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA [3] School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK.

ABSTRACT
Self-assembled, epitaxially grown InAs/GaAs quantum dots (QDs) are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications. However, self-assembled growth results in an essentially random in-plane spatial distribution of QDs, presenting a challenge in creating devices that exploit the strong interaction of single QDs with highly confined optical modes. Here, we present a photoluminescence imaging approach for locating single QDs with respect to alignment features with an average position uncertainty <30 nm (<10 nm when using a solid-immersion lens), which represents an enabling technology for the creation of optimized single QD devices. To that end, we create QD single-photon sources, based on a circular Bragg grating geometry, that simultaneously exhibit high collection efficiency (48%±5% into a 0.4 numerical aperture lens, close to the theoretically predicted value of 50%), low multiphoton probability (g(2)(0) <1%), and a significant Purcell enhancement factor (≈3).

No MeSH data available.


Related in: MedlinePlus

Performance of the two-colour positioning technique.(a) EMCCD image of the photoluminescence from a single QD and reflected light by the alignment marks (metallic crosses), acquired by illuminating the sample simultaneously with both the red and near-infrared LEDs. (b) Orthogonal line cuts (horizontal=x axis, vertical=y axis) of the photoluminescence image, showing the profiles of the QD emission (solid symbols) and of the image of the alignment marks (open symbols) and their Gaussian fits (solid lines). (c) Histograms of the uncertainties of the QD and alignment mark positions and QD-alignment mark separations, measured from the Gaussian fits of line cuts from 45 images. The uncertainties represent one standard deviation values determined by a nonlinear least squares fit of the data. (d,e) Photoluminescence imaging through a solid-immersion lens. (d) Image of the photoluminescence from single QDs and reflected light from the alignment marks (metallic crosses), collected under the 630 nm/940 nm co-illumination scheme. (e) y axis line cuts from the photoluminescence image, showing the profiles of the QD emission (solid symbols) and reflected light from the alignment mark (open symbols). The solid lines are nonlinear least squares fits to Gaussians.
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f2: Performance of the two-colour positioning technique.(a) EMCCD image of the photoluminescence from a single QD and reflected light by the alignment marks (metallic crosses), acquired by illuminating the sample simultaneously with both the red and near-infrared LEDs. (b) Orthogonal line cuts (horizontal=x axis, vertical=y axis) of the photoluminescence image, showing the profiles of the QD emission (solid symbols) and of the image of the alignment marks (open symbols) and their Gaussian fits (solid lines). (c) Histograms of the uncertainties of the QD and alignment mark positions and QD-alignment mark separations, measured from the Gaussian fits of line cuts from 45 images. The uncertainties represent one standard deviation values determined by a nonlinear least squares fit of the data. (d,e) Photoluminescence imaging through a solid-immersion lens. (d) Image of the photoluminescence from single QDs and reflected light from the alignment marks (metallic crosses), collected under the 630 nm/940 nm co-illumination scheme. (e) y axis line cuts from the photoluminescence image, showing the profiles of the QD emission (solid symbols) and reflected light from the alignment mark (open symbols). The solid lines are nonlinear least squares fits to Gaussians.

Mentions: Figure 2a shows an image taken when the sample is co-illuminated by both 630 and 940 nm LEDs, with the 940-nm power set to be ≈4 μW, about four orders of magnitude smaller than that of the 630-nm LED power. Orthogonal line scans through the QD and alignment marks under this co-illumination scheme are shown in Fig. 2b. As expected, the uncertainty values determined for QD and alignment mark positions are larger than those obtained when acquiring two separate images (Fig. 1c,e), for which the LED power can be optimized independently to maximize the image contrast and minimize each uncertainty. However, we have favoured the co-illumination approach due to its ability to reduce some potential uncertainties, like sample drift, that may occur during schemes requiring multiple images to be acquired. Ultimately, one might envision time-multiplexing and drift compensation techniques being employed to correct for such factors.


Nanoscale optical positioning of single quantum dots for bright and pure single-photon emission.

Sapienza L, Davanço M, Badolato A, Srinivasan K - Nat Commun (2015)

Performance of the two-colour positioning technique.(a) EMCCD image of the photoluminescence from a single QD and reflected light by the alignment marks (metallic crosses), acquired by illuminating the sample simultaneously with both the red and near-infrared LEDs. (b) Orthogonal line cuts (horizontal=x axis, vertical=y axis) of the photoluminescence image, showing the profiles of the QD emission (solid symbols) and of the image of the alignment marks (open symbols) and their Gaussian fits (solid lines). (c) Histograms of the uncertainties of the QD and alignment mark positions and QD-alignment mark separations, measured from the Gaussian fits of line cuts from 45 images. The uncertainties represent one standard deviation values determined by a nonlinear least squares fit of the data. (d,e) Photoluminescence imaging through a solid-immersion lens. (d) Image of the photoluminescence from single QDs and reflected light from the alignment marks (metallic crosses), collected under the 630 nm/940 nm co-illumination scheme. (e) y axis line cuts from the photoluminescence image, showing the profiles of the QD emission (solid symbols) and reflected light from the alignment mark (open symbols). The solid lines are nonlinear least squares fits to Gaussians.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525159&req=5

f2: Performance of the two-colour positioning technique.(a) EMCCD image of the photoluminescence from a single QD and reflected light by the alignment marks (metallic crosses), acquired by illuminating the sample simultaneously with both the red and near-infrared LEDs. (b) Orthogonal line cuts (horizontal=x axis, vertical=y axis) of the photoluminescence image, showing the profiles of the QD emission (solid symbols) and of the image of the alignment marks (open symbols) and their Gaussian fits (solid lines). (c) Histograms of the uncertainties of the QD and alignment mark positions and QD-alignment mark separations, measured from the Gaussian fits of line cuts from 45 images. The uncertainties represent one standard deviation values determined by a nonlinear least squares fit of the data. (d,e) Photoluminescence imaging through a solid-immersion lens. (d) Image of the photoluminescence from single QDs and reflected light from the alignment marks (metallic crosses), collected under the 630 nm/940 nm co-illumination scheme. (e) y axis line cuts from the photoluminescence image, showing the profiles of the QD emission (solid symbols) and reflected light from the alignment mark (open symbols). The solid lines are nonlinear least squares fits to Gaussians.
Mentions: Figure 2a shows an image taken when the sample is co-illuminated by both 630 and 940 nm LEDs, with the 940-nm power set to be ≈4 μW, about four orders of magnitude smaller than that of the 630-nm LED power. Orthogonal line scans through the QD and alignment marks under this co-illumination scheme are shown in Fig. 2b. As expected, the uncertainty values determined for QD and alignment mark positions are larger than those obtained when acquiring two separate images (Fig. 1c,e), for which the LED power can be optimized independently to maximize the image contrast and minimize each uncertainty. However, we have favoured the co-illumination approach due to its ability to reduce some potential uncertainties, like sample drift, that may occur during schemes requiring multiple images to be acquired. Ultimately, one might envision time-multiplexing and drift compensation techniques being employed to correct for such factors.

Bottom Line: Self-assembled, epitaxially grown InAs/GaAs quantum dots (QDs) are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications.However, self-assembled growth results in an essentially random in-plane spatial distribution of QDs, presenting a challenge in creating devices that exploit the strong interaction of single QDs with highly confined optical modes.Here, we present a photoluminescence imaging approach for locating single QDs with respect to alignment features with an average position uncertainty <30 nm (<10 nm when using a solid-immersion lens), which represents an enabling technology for the creation of optimized single QD devices.

View Article: PubMed Central - PubMed

Affiliation: 1] Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA [2] Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA [3] School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK.

ABSTRACT
Self-assembled, epitaxially grown InAs/GaAs quantum dots (QDs) are promising semiconductor quantum emitters that can be integrated on a chip for a variety of photonic quantum information science applications. However, self-assembled growth results in an essentially random in-plane spatial distribution of QDs, presenting a challenge in creating devices that exploit the strong interaction of single QDs with highly confined optical modes. Here, we present a photoluminescence imaging approach for locating single QDs with respect to alignment features with an average position uncertainty <30 nm (<10 nm when using a solid-immersion lens), which represents an enabling technology for the creation of optimized single QD devices. To that end, we create QD single-photon sources, based on a circular Bragg grating geometry, that simultaneously exhibit high collection efficiency (48%±5% into a 0.4 numerical aperture lens, close to the theoretically predicted value of 50%), low multiphoton probability (g(2)(0) <1%), and a significant Purcell enhancement factor (≈3).

No MeSH data available.


Related in: MedlinePlus