Deterministically integrating semiconductor quantum emitters [1] with plasmonic nano-devices [2,3] paves the way towards chip-scale integrable [4], true nanoscale quantum photonics technologies [5]. For this purpose, stable and bright semiconductor emitters [6] are needed, which moreover allow for CMOS-compatibility [7] and optical activity in the telecommunication band [8]. Here, we demonstrate strongly enhanced light-matter coupling of single near-surface (< 10 nm) InAs quantum dots monolithically integrated into electromagnetic hot-spots of sub-wavelength sized metal nanoantennas. The antenna strongly enhances the emission intensity of single quantum dots by up to ∼ 16×, an effect accompanied by an up to 3.4× Purcell-enhanced spontaneous emission rate. Moreover, the emission is strongly polarised along the antenna axis with degrees of linear polarisation up to ∼ 85 %. The results unambiguously demonstrate the efficient coupling of individual quantum dots to state-of-the-art nanoantennas. Our work provides new perspectives for the realisation of quantum plasmonic sensors [9], step-changing photovoltaic devices [10], bright and ultrafast quantum light sources [11] and efficent nano-lasers [12].The field of nanoplasmonics [13] has already demonstrated outstanding potential to tailor and enhance electromagnetic fields on sub-wavelength lengthscales [3]. As such it represents the most promising route to interface state-of-the-art electronics with true nano-photonic devices on the same chip [7]. To this end, the study, optimisation and integration of nano-scale plasmonic components, such as antennas [14] and waveguides [4], on highquality semiconductor substrates [15] is essential in order to prove their applicability in real-world applications. Monolithically integrated, self-assembled quantum dots [1] exhibit outstanding electrical and optical properties, they do not suffer from bleaching or blinking and have near-unity internal quantum efficiencies. These properties stem from the efficient decoupling from environmental perturbations in the solid-state matrix material and distinguish self-assembled quantum dots from alternative quantum emitters, such as nitrogen vacancy centres [16], colloidal nano-crystals [6], single molecules [17] or fluorescent dyes [18]. Lithographically defined plasmonic dimer antennas, such as bowties [14], are most prominent amongst the zoo of metallic nanoparticles since they simultaneously provide strong light confinement in subwavelength sized hot-spots, large-range spectral tunability and facilitate electrical access [19] and full control of the emission polarisation [20]. As a result, the quantum dot coupled nanoantennas offer new perspectives to probe light-matter-couplings and cavity quantum electrodynamics (cQED) effects beyond the point-dipole approximation [21].In this Letter, we coupled individual quantum dots to plasmonic nanoantennas to form a novel cQED-system schematically illustrated in figure 1 (a), which consists of near-surface (d ∼ 10 nm) InAs/AlGaAs quantum dots [22] ...

In this work, we study metal droplets on a semiconductor surface that are the initial stage for both droplet epitaxy and local droplet etching. The distributions of droplet geometrical parameters such as height, radius and volume help to understand the droplet formation that strongly influences subsequent nanohole etching. To investigate the etching and intermixing processes, we offer a new method of wetting angle analysis. The aspect ratio that is defined as the ratio of the height to radius was used as an estimation of wetting angle which depends on the droplet material. The investigation of the wetting angle and the estimation of indium content revealed significant materials intermixing during the deposition time. AFM measurements reveal the presence of two droplet groups that is in agreement with nanohole investigations. To explain this observation, we consider arsenic evaporation and consequent change in the initial substrate. On the basis of our analysis, we suggest the model of droplet evolution and the formation of two droplet groups.

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Metal droplets are prominent candidates for plasmonic antennas for semiconductor quantum dots (QDs) due to compatibility with molecular beam epitaxy (MBE). They can be produced in a self-assembly process directly in the MBE chamber on substrates with buried QDs, forming vertically aligned QD-droplet pairs and thus opening the way for the synthesis of novel hybrid metal−semiconductor structures. In this paper, we have numerically studied the surface plasmon resonance in lens-shaped droplets consisted of group III metals focusing on the influence of the droplet material and tuning of the resonance position. The discrete dipole approximation method was used for simulations, and typical experimental parameters were considered. Indium was demonstrated to be efficient for plasmonic applications in the near-infrared region. The resonance position redshifts linearly with increasing droplet size and can be tuned in a wide range to match InAs/GaAs QDs emission. Large droplets support multipolar modes with specific polarization and incidence angle dependences that can be used for multichannel selective plasmonic nanoantennas. Nanodroplets of group III metals present efficient and highly tunable plasmonic structures that along with self-assemble formation make them attractive for solid-state nanophonotics.

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