InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids

Semiconductor quantum dots (QDs) have been demonstrated viable for efficient light emission applications, in particular for the emission of single photons on demand. However, the preparation of QDs emitting photons with predefined and deterministic polarization vectors has proven arduous. Access to linearly polarized photons is essential for various applications. In this report, a novel concept to directly generate linearly-polarized photons is presented. This concept is based on InGaN QDs grown on top of elongated GaN hexagonal pyramids, by which the predefined elongation determines the polarization vectors of the emitted photons from the QDs. This growth scheme should allow fabrication of ultracompact arrays of photon emitters, with a controlled polarization direction for each individual emitter. Keywords: GaN; InGaN; photoluminescence; polarized emission; quantum dot INTRODUCTION Quantum dots (QDs) have validated their important role in current optoelectronic devices and they are also seen promising as light sources for quantum information applications. An improved efficiency of laser diodes and light-emitting diodes can be achieved by the incorporation of QDs ensembles in the optically active layers.1 In addition, the proposed quantum computer applications rely on photons with distinct energy and polarization vectors, which can be seen as the ultimate demand on photons emitted from individual QDs.2 A common requirement raised for several optoelectronic applications, e.g., liquid-crystal displays, three-dimensional visualization, (bio)-dermatology 3 and the optical quantum computers, 4 is the need of linearly polarized light for their operation. For existing applications, the generation of linearly polarized light is obtained by passing unpolarized light through a combination of polarization selective filters and waveguides, with an inevitable efficiency loss as the result. These losses can be drastically reduced by employment of sources, which directly generate photons with desired polarization directions.Conventional QDs grown via the Stranski-Krastanov (SK) growth mode are typically randomly distributed over planar substrates and possess different degrees of anisotropies. The anisotropy in strain field and/or geometrical shape of each individual QD determines the polarization performance of the QD emission. Accordingly, a cumbersome post-selection of QDs with desired polarization properties among the randomly distributed QDs is required for device integration.

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“…11, 26 The full-width half-maxima of the emission peaks in the present case are relatively broad (. 4 meV).…”

Section: Multiple Ingan Qds On a Gan Ehpmentioning

confidence: 60%

Direct generation of linearly polarized photon emission with designated orientations from site-controlled InGaN quantum dots

et al. 2014

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“…12 A promising approach for fabrication of nitride-based QDs is to deposit a thin layer of InGaN on top of hexagonal GaN micro pyramids formed by selective area growth. 13 Pyramids grown with this approach have been shown to exhibit single and sharp InGaN related emission lines with high degree of linear polarization, indicating the formation of one asymmetric site-controlled InGaN quantum dot on each pyramid. 14 Moreover, a simple elongation of the pyramid base gives control of the polarization direction of the InGaN emission, as it is found to be well-aligned with the designed elongation.…”

mentioning

confidence: 94%

“…The structure is then covered by a layer of GaN to finalize the formation of QD inclusions in the tip of the pyramids. 13 The pyramids have a base diameter of 3 lm, and they are ordered in square 21 Â 21 arrays with 5.5 lm pitch.…”

mentioning

confidence: 99%

Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot

Jemsson

Machhadani

Karlsson

et al. 2014

Applied Physics Letters

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We report on the observation of linearly polarized single photon antibunching in the excitonic emission from a site-controlled InGaN quantum dot. The measured second order coherence function exhibits a significant dip at zero time difference, corresponding to g(m)(2) (0) = 0: 90 under continuous laser excitation. This relatively high value of g(m)(2) (0) is well understood by a model as the combination of short exciton life time (320 ps), limited experimental timing resolution and the presence of an uncorrelated broadband background emission from the sample. Our result provides the first rigorous evidence of InGaN quantum dot formation on hexagonal GaN pyramids, and it highlights a great potential in these dots as fast polarized single photon emitters if the background emission can be eliminated.

Funding Agencies|Carl Trygger Foundation for Scientific Research; Swedish Research Council (VR); Nano-N consortium - Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Font-D, at Linkoping University

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“…The potential of such pyramids for the growth of arrays of InGaN nanostructures was identified long ago: indeed, deposition of InGaN on fully formed, untruncated GaN pyramids and further covering with GaN barrier/cap layer leads to the formation of inclined InGaN quantum wells on the side facets [26]. In addition, it has been further demonstrated that this technique also leads to formation of QDs at the apex of the pyramid [27,28].…”

Section: Selective Area Growth Of Nwsmentioning

confidence: 99%

III-Nitride quantum dots in nanowires: growth, structural, and optical properties

Daudin¹

2014

Turk J Phys

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Nanowires (NWs) have emerged as a platform to build complex, self-assembled, defect-free nanostructures.In particular, the growth of single islands/disks of various III-nitride combinations (InGaN in GaN, GaN in AlN, AlGaN in AlN) are possible in NW heterostructures, extending the field of experimental quantum dot exploration. Specific to NWs, the possibility to disperse them paves the way to probe and investigate only a single wire/dot.In the present article, the growth of GaN disks/islands and InGaN islands as well as their optical properties at the nanometer scale will be reviewed. Besides the intentional growth of QD-in NW heterostructures, special attention will be paid to compositional fluctuations in ternary alloy nanowires, which also lead to a quantum dot-like behavior. Specific to NW geometry, optical emission is expected to exhibit a high degree of polarization along the NW axis, opening a pathway to the practical realization of polarized single photon emitters in a wide range of wavelengths.

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InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids

Cited by 26 publications

References 28 publications

Direct generation of linearly polarized photon emission with designated orientations from site-controlled InGaN quantum dots

Direct generation of linearly polarized photon emission with designated orientations from site-controlled InGaN quantum dots

Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot

III-Nitride quantum dots in nanowires: growth, structural, and optical properties

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