InAs/InP Quantum Dots

• InAs/InP quantum dots are nanoscale semiconductor structures that confine carriers in InAs-rich regions within InP barriers, enabling telecom-band single photon emission.
• They are fabricated via self-assembly, droplet epitaxy, and nanowire heterostructures, providing precise control over morphology, symmetry, and density.
• Integrated with photonic circuits and electrical tuning, these dots support advanced optoelectronic applications in quantum communication and telecom technologies.

InAs/InP quantum dots are nanoscale confinement structures in which carriers are localized in InAs or InAs-rich InAsP/InAs(P) regions within InP or lattice-matched InP-based barriers. They are realized as self-assembled planar dots, droplet-epitaxy dots, and axially defined nanowire heterostructures, and they support excitonic, spin, transport, and photonic functionalities spanning single-photon emission in the telecommunication bands, electrically tunable spectra, small fine-structure splitting in high-symmetry geometries, and hard-wall few-level transport (Wasiluk et al., 11 Jul 2025, Ha et al., 2016, Thomas et al., 2019).

1. Structural archetypes and material scope

The InAs/InP literature is not limited to a single morphology. Planar self-assembled emitters include symmetric, self-assembled InAs(P) quantum dots embedded directly in an InP matrix and grown by molecular beam epitaxy on an Fe-doped InP substrate, with a post-growth ripening step reducing the areal density to approximately $2\times10^9~\mathrm{cm}^{-2}$. In one such C-band platform, the dots are lens-shaped, with diameter $55 \pm 15~\mathrm{nm}$ and height $15~\mathrm{nm}$, sit atop a 25-pair InP/InAlGaAs DBR, and reach a photon extraction efficiency of $13.3\%$ into a 0.4 numerical aperture objective when integrated in non-deterministically fabricated cylindrical mesas (Wasiluk et al., 11 Jul 2025).

A second major class comprises droplet-epitaxy dots. On InP(111)A, droplet epitaxy produces laterally symmetric InAs dots whose emission can be tuned from $1.3$ to $1.7~\mu\mathrm{m}$ and beyond $1.8~\mu\mathrm{m}$ by changing the lattice-matched In(Al,Ga)As barrier composition; on InP(001), droplet epitaxy with post-growth annealing produces low-density arrays with $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$, etched pits, concave bases, and highly symmetric in-plane profiles (Ha et al., 2016, Holewa et al., 2021).

A third class is formed by nanowire heterostructures. In transport devices, the quantum dot is an axial InAs segment confined by epitaxial InP barriers, for example a $20 \pm 1~\mathrm{nm}$ InAs island between $\approx 4~\mathrm{nm}$ InP barriers or a $55 \pm 15~\mathrm{nm}$0 InAs segment between two $55 \pm 15~\mathrm{nm}$1 InP barriers. In photonic nanowires, site-selected InAsP/InP dots are embedded in tapered InP waveguides designed to couple emission into the $55 \pm 15~\mathrm{nm}$2 mode (Prete et al., 2019, Thomas et al., 2019, Haffouz et al., 2018).

Architecture	Representative structural characteristics	Representative results
Planar self-assembled InAs(P)/InP	Lens-shaped; $55 \pm 15~\mathrm{nm}$3 diameter; $55 \pm 15~\mathrm{nm}$4 height; density $55 \pm 15~\mathrm{nm}$5	C-band emission; $55 \pm 15~\mathrm{nm}$6; $55 \pm 15~\mathrm{nm}$7 extraction (Wasiluk et al., 11 Jul 2025)
Droplet-epitaxy InAs/InP	InP(111)A or InP(001); symmetric profiles; densities from $55 \pm 15~\mathrm{nm}$8 to $55 \pm 15~\mathrm{nm}$9	$15~\mathrm{nm}$0 to $15~\mathrm{nm}$1 tuning; $15~\mathrm{nm}$2 single-photon purity (Ha et al., 2016, Holewa et al., 2021)
Axial InAs/InP nanowire QDs	InAs segment $15~\mathrm{nm}$3 to $15~\mathrm{nm}$4; InP barriers $15~\mathrm{nm}$5 to $15~\mathrm{nm}$6	$15~\mathrm{nm}$7 tunable from $15~\mathrm{nm}$8 to $15~\mathrm{nm}$9; $13.3\%$0 (Thomas et al., 2019, Prete et al., 2019)
Integrated photonic realizations	Tapered InP waveguides on SOI or photonic nanowires	$13.3\%$1 directional on-chip coupling; $13.3\%$2 to $13.3\%$3 O-band brightness increase (Burakowski et al., 2023, Haffouz et al., 2018)

Closely related alloyed realizations recur throughout this literature. InAsP/InP and InAs(P)/InP appear in telecom photon-source, spin, and nanowire studies because the relevant confinement remains InP-based and the same device themes—telecom emission, excitonic complexes, and photonic integration—persist across these compositionally mixed systems (Elvira et al., 2011, Wasiluk et al., 11 Jul 2025).

2. Growth modes, symmetry control, and density engineering

Growth mode is the primary determinant of shape anisotropy. A common simplification is that InAs/InP dots are intrinsically elongated because conventional Stranski–Krastanov growth on InP(100) often produces elongated “wires” or “dashes.” The record is more differentiated. Droplet epitaxy on the $13.3\%$4-symmetric InP(111)A surface yields laterally symmetric dots with identical AFM cross-sections along $13.3\%$5 and $13.3\%$6, whereas annealed droplet-epitaxy dots on InP(001) exhibit an aspect ratio of 1.09, compared with 1.75 for the unannealed reference sample (Ha et al., 2016, Holewa et al., 2021).

On InP(111)A, barrier-band-gap engineering provides wavelength control without substantially changing the dot shape distribution. Three lattice-matched barriers—$13.3\%$7, $13.3\%$8, and $13.3\%$9—systematically red-shift the emission by reducing both conduction- and valence-band offsets, while AFM shows that the dot sizes remain narrowly distributed and essentially independent of barrier alloy. The dots are flat and disk-like, with heights corresponding to roughly $1.3$0–$1.3$1 monolayers, and the measured diameter-height relation is $1.3$2 in nanometers (Ha et al., 2016).

On InP(001), a different route to symmetry is annealed droplet epitaxy in etched pits. Every QD resides at the center of a pit formed during the $1.3$3 anneal; the pits are asymmetric in lateral extent, but the QD bases are nearly rotationally symmetric. STEM and EDX identify truncated-cone buried dots with base diameter $1.3$4, top diameter $1.3$5, height $1.3$6, and composition $1.3$7 with $1.3$8. The concave base, induced by capillarity- and strain-driven redistribution, is central to the symmetry of the confining potential (Holewa et al., 2021).

Near-critical Stranski–Krastanov growth adds a further degree of control. In low-pressure MOVPE on InP(001), the dot density can be tuned between $1.3$9 and $1.7~\mu\mathrm{m}$0 by working close to the critical wetting-layer thickness and varying InAs coverage and V/III ratio, while the dot size is tuned almost independently through the growth interruption. At fixed coverage, increasing the interruption from $1.7~\mu\mathrm{m}$1 to $1.7~\mu\mathrm{m}$2 raises the median height from $1.7~\mu\mathrm{m}$3 to $1.7~\mu\mathrm{m}$4–$1.7~\mu\mathrm{m}$5 with negligible change in density, which is the central operational result of the near-critical method (Berdnikov et al., 2023).

Other selective-area routes exist, but they introduce their own trade-offs. Selective-area droplet epitaxy assisted by PS-b-PDMS block copolymer lithography yields site-controlled InAs/InP arrays emitting around $1.7~\mu\mathrm{m}$6, yet temperature-dependent spectroscopy indicates a density of states in the InP bandgap in the vicinity of the QDs, attributed to lithographic residuals, plasma damage, and incomplete de-oxidation; these defect states substantially impact carrier capture and thermal quenching (Shikin et al., 2018).

3. Electronic structure, excitonic complexes, and fine structure

The electronic structure of InAs/InP dots is governed by the combined action of strain, band offsets, geometry, and atomistic disorder. Atomistic empirical tight-binding calculations that scan the valence band offset from $1.7~\mu\mathrm{m}$7 to $1.7~\mu\mathrm{m}$8 show that overall confinement is a nontrivial interplay of strain effects and valence band offset. In strained disk-type dots, hole states become single-band-like with clear $1.7~\mu\mathrm{m}$9-, $1.8~\mu\mathrm{m}$0-, and $1.8~\mu\mathrm{m}$1-shell organization, with $1.8~\mu\mathrm{m}$2–$1.8~\mu\mathrm{m}$3 spacings of $1.8~\mu\mathrm{m}$4–$1.8~\mu\mathrm{m}$5 and $1.8~\mu\mathrm{m}$6-shell splittings of a few meV; in lens-type InAs/InP dots, strain is essential for recovering shell-like hole spectra (Zieliński, 2013).

Excitonic complexes follow a characteristic hierarchy. In atomistic theory for wurtzite InAsP/InP nanowire dots, the low-energy electron and hole states form electronic shells only weakly affected by hexagonal symmetry and As fluctuations, while the relative alignment of exciton, trion, and biexciton lines agrees with zincblende InAs/InP in that biexcitons and positive trions are only weakly bound. Random As distributions generate dot-to-dot fluctuations of a few meV in single-particle and many-body transitions, while the exciton fine-structure splitting remains of order a few $1.8~\mu\mathrm{m}$7 with significant random fluctuations (Cygorek et al., 2019).

Measured spectra on isolated emitters reflect the same basic organization, though with geometry-dependent details. In low-density MOVPE-grown flat QDs on InP(001), a neutral exciton–biexciton cascade in the L band shows $1.8~\mu\mathrm{m}$8, $1.8~\mu\mathrm{m}$9, biexciton binding energy $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$0, and fine-structure splitting $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$1. Charged excitons in the S, C, and L bands are identified by near-linear power dependence and absence of fine-structure splitting (Holewa et al., 2019).

The magnitude of the fine-structure splitting depends strongly on symmetry. For disk-type dots in the tight-binding study, the anisotropic bright-doublet splitting is $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$2 in InAs/InP and $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$3 in InAs/GaAs, whereas lens-type dots give $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$4 in the range $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$5–$n \approx 2.8\times10^8~\mathrm{cm}^{-2}$6. In droplet-epitaxy InAs/InP on InP(001), the ensemble degree of linear polarization is $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$7, suggesting negligible ensemble-averaged FSS, but single-QD micro-PL from etched mesas gives $n \approx 2.8\times10^8~\mathrm{cm}^{-2}$8, a value attributed to destructive changes made in the QD environment during post-growth processing. In that context the splitting is written as

$n \approx 2.8\times10^8~\mathrm{cm}^{-2}$9

This combination of ensemble symmetry and processing-sensitive single-dot anisotropy is one of the central nuances of the InAs/InP platform (Holewa et al., 2021).

Magneto-optical theory adds a further layer. Eight-band envelope-function calculations for cylindrical InAs/InP dots under axial magnetic field show that the electron $20 \pm 1~\mathrm{nm}$0-factor is controlled by the amplitude of valence-state envelope functions with non-zero orbital momentum. As height or radius decreases, orbital angular momentum is quenched and $20 \pm 1~\mathrm{nm}$1 moves toward $20 \pm 1~\mathrm{nm}$2; over the studied sizes the computed range spans roughly from about $20 \pm 1~\mathrm{nm}$3 up to $20 \pm 1~\mathrm{nm}$4. The same calculations show that remote-band contributions reduce agreement between theory and experiment, while Coulomb interaction improves the description of exciton diamagnetic coefficients (Bree et al., 2011).

4. Telecom emission, radiative dynamics, and single-photon operation

Telecom-band emission is one of the defining attributes of the InAs/InP family. C-band single dots embedded directly in InP can emit with single-photon purity $20 \pm 1~\mathrm{nm}$5, and the key transitions observed in polarization-resolved photoluminescence include the neutral exciton $20 \pm 1~\mathrm{nm}$6, biexciton $20 \pm 1~\mathrm{nm}$7, and charged complexes $20 \pm 1~\mathrm{nm}$8 and $20 \pm 1~\mathrm{nm}$9, all within the C-band (Wasiluk et al., 11 Jul 2025). Low-density MOVPE-grown InAs/InP QD-like structures on InP(001) cover $\approx 4~\mathrm{nm}$0–$\approx 4~\mathrm{nm}$1, with peaks D, E, and F lying in the L, C, and S bands, respectively, while ripening-assisted InAs/InAlGaAs/InP(001) structures broaden the accessible range to $\approx 4~\mathrm{nm}$2–$\approx 4~\mathrm{nm}$3 (Holewa et al., 2019, Holewa et al., 2020).

Barrier engineering is an established route to spectral extension. On InP(111)A, the peak emission wavelength can be changed systematically from $\approx 4~\mathrm{nm}$4 to $\approx 4~\mathrm{nm}$5 by tuning the ternary alloy composition of In(Al,Ga)As barriers lattice-matched to InP, and the reddest sample extends beyond $\approx 4~\mathrm{nm}$6, reaching the L and U telecom bands (Ha et al., 2016). In nanowires, site-selected InAsP/InP quantum dots have been demonstrated from $\approx 4~\mathrm{nm}$7 to $\approx 4~\mathrm{nm}$8, and emission-wavelength-optimized waveguides can raise the saturated count rate in the O-band from $\approx 4~\mathrm{nm}$9 to $55 \pm 15~\mathrm{nm}$00 (Haffouz et al., 2018).

Radiative lifetimes are typically in the nanosecond range but are not universally monotonic with wavelength or size. In ripened InAs/InAlGaAs/InP dots, time-resolved photoluminescence gives a nearly dispersionless lifetime of $55 \pm 15~\mathrm{nm}$01 across the spectrally broad emission, with the G family reaching $55 \pm 15~\mathrm{nm}$02. In low-density flat InAs/InP dots, exciton radiative lifetimes are also $55 \pm 15~\mathrm{nm}$03 with weak dispersion across emission energies; the explanation advanced there is that height-dependent Coulomb correlations counterbalance the usual $55 \pm 15~\mathrm{nm}$04 radiative scaling (Holewa et al., 2020, Holewa et al., 2019).

Single-photon operation has been demonstrated in several architectures, but the metrics depend strongly on geometry and collection optics. In directly bonded InP-on-SOI devices, a neutral exciton collected from the cleaved silicon-waveguide facet under cw excitation shows $55 \pm 15~\mathrm{nm}$05, corresponding to “suppressed multi-photon generation events exhibiting 80% single photon generation purity,” and the directional on-chip coupling into the Si waveguide is estimated as $55 \pm 15~\mathrm{nm}$06 (Burakowski et al., 2023). In droplet-epitaxy InAs/InP on InP(001), the reported raw single-photon purity is $55 \pm 15~\mathrm{nm}$07 in the third telecom window (Holewa et al., 2021). In earlier MOCVD-grown InAsP/InP mesas, the normalized central HBT peak at $55 \pm 15~\mathrm{nm}$08 is $55 \pm 15~\mathrm{nm}$09, confirming antibunched single-photon emission in the O-band (Elvira et al., 2011).

A recurrent complication at longer wavelengths is the appearance of a broad background. In single InAsP/InP dots, sharp lines above $55 \pm 15~\mathrm{nm}$10 are superimposed on a broad background that intensifies with pump power. The work identifies this background as cascaded multiexciton recombination within the same dot rather than wetting-layer or defect emission, a distinction that matters for interpreting C-band spectra and for cavity-feeding strategies (Elvira et al., 2011).

Thermal activation and redistribution also shape telecom performance. In the high-density ensemble study on InP substrates, both QDots and QDashes exhibit two-stage quenching in Arrhenius fits,

$55 \pm 15~\mathrm{nm}$11

with $55 \pm 15~\mathrm{nm}$12 in the $55 \pm 15~\mathrm{nm}$13–$55 \pm 15~\mathrm{nm}$14 range and $55 \pm 15~\mathrm{nm}$15 up to $55 \pm 15~\mathrm{nm}$16. The lower-energy process is assigned to coupled-excited-state redistribution, while the higher-energy process follows $55 \pm 15~\mathrm{nm}$17, which the authors interpret as quasi-correlated electron-hole escape (Jahan et al., 2012).

5. Spin dynamics, magneto-optics, and electrical spectral tuning

Spin control in telecom InAs/InP dots has advanced from static spectroscopy to direct dephasing measurements. In a single InAs(P)/InP C-band dot, quasi-resonant circularly polarized excitation at $55 \pm 15~\mathrm{nm}$18 identifies a negatively charged trion through negative circular polarization. The degree of circular polarization is defined as

$55 \pm 15~\mathrm{nm}$19

and for the $55 \pm 15~\mathrm{nm}$20 line it reaches $55 \pm 15~\mathrm{nm}$21 at zero field, while the neutral exciton shows negligible circular polarization (Wasiluk et al., 11 Jul 2025).

The same work gives the first Hanle-effect demonstration in single telecom InAs(P)/InP dots. In Voigt geometry, the $55 \pm 15~\mathrm{nm}$22 polarization follows a Lorentzian depolarization,

$55 \pm 15~\mathrm{nm}$23

with half-width at half-maximum $55 \pm 15~\mathrm{nm}$24. Using $55 \pm 15~\mathrm{nm}$25, the extracted inhomogeneous electron spin dephasing time is

$55 \pm 15~\mathrm{nm}$26

yielding $55 \pm 15~\mathrm{nm}$27. Despite indium’s large nuclear spin $55 \pm 15~\mathrm{nm}$28, the measured $55 \pm 15~\mathrm{nm}$29 is comparable to values reported for GaAs dots, which the authors attribute to the larger dot volume and the corresponding $55 \pm 15~\mathrm{nm}$30 suppression of Overhauser fluctuations (Wasiluk et al., 11 Jul 2025).

Electrical tuning of optical transitions is another mature capability. In capacitor-like InAs/InP Stark devices with a $55 \pm 15~\mathrm{nm}$31 PECVD $55 \pm 15~\mathrm{nm}$32 insulator, continuous Stark redshifts up to $55 \pm 15~\mathrm{nm}$33, corresponding to $55 \pm 15~\mathrm{nm}$34, are obtained without spectral jumps to charged states. The shift follows the quantum-confined Stark effect,

$55 \pm 15~\mathrm{nm}$35

or, in the fitted form used there, $55 \pm 15~\mathrm{nm}$36, with $55 \pm 15~\mathrm{nm}$37 and $55 \pm 15~\mathrm{nm}$38 in the reported units (Aghaeimeibodi et al., 2018).

The usable Stark range is limited not by charge instabilities but by tunneling. The integrated PL intensity drops to $55 \pm 15~\mathrm{nm}$39 of the zero-field value at $55 \pm 15~\mathrm{nm}$40, while the lifetime evolves from $55 \pm 15~\mathrm{nm}$41 at $55 \pm 15~\mathrm{nm}$42 to $55 \pm 15~\mathrm{nm}$43 at $55 \pm 15~\mathrm{nm}$44 and then decreases to $55 \pm 15~\mathrm{nm}$45 at higher fields. The initial increase is attributed to reduced oscillator strength as electron and hole separate, and the subsequent decrease to field-induced carrier tunneling. Throughout much of the tuning range the single-photon character is preserved, with $55 \pm 15~\mathrm{nm}$46 at $55 \pm 15~\mathrm{nm}$47 and $55 \pm 15~\mathrm{nm}$48 at $55 \pm 15~\mathrm{nm}$49 (Aghaeimeibodi et al., 2018).

These spin and Stark results also delimit common misunderstandings. The nanosecond-scale $55 \pm 15~\mathrm{nm}$50 value is explicitly an inhomogeneous dephasing time dominated by frozen Overhauser fluctuations under continuous excitation and finite integration times, not a spin-echo coherence time. Likewise, the large Stark-tuning range does not remove tunneling or brightness trade-offs; it postpones charge-state jumps by blocking carrier injection from the contacts (Wasiluk et al., 11 Jul 2025, Aghaeimeibodi et al., 2018).

6. Integrated photonics, transport functionality, and non-ideal channels

InAs/InP dots have been coupled to both III–V and silicon photonic circuits. A direct-bonding route hybridizes InP and SOI chips without an intermediate layer, using oxygen-plasma-activated surfaces, vacuum bonding at $55 \pm 15~\mathrm{nm}$51 and $55 \pm 15~\mathrm{nm}$52, and outgassing channels in the silicon. Bonding yield exceeds $55 \pm 15~\mathrm{nm}$53 on a quarter of a 2-inch InP wafer. In the finished device, a self-assembled InAs/InP dot sits in a $55 \pm 15~\mathrm{nm}$54-thick InP waveguide above a $55 \pm 15~\mathrm{nm}$55-thick Si waveguide, with a $55 \pm 15~\mathrm{nm}$56 taper transferring light into the silicon layer; measured directional on-chip coupling into the Si waveguide is $55 \pm 15~\mathrm{nm}$57 (Burakowski et al., 2023).

The same platform also illustrates the importance of broadband, non-cavity coupling. Finite-difference time-domain simulations predict directional dipole coupling into guided TE modes of $55 \pm 15~\mathrm{nm}$58–$55 \pm 15~\mathrm{nm}$59, taper transmission $55 \pm 15~\mathrm{nm}$60–$55 \pm 15~\mathrm{nm}$61, cleaved-facet outcoupling $55 \pm 15~\mathrm{nm}$62–$55 \pm 15~\mathrm{nm}$63, and in-plane collection efficiency $55 \pm 15~\mathrm{nm}$64 of $55 \pm 15~\mathrm{nm}$65–$55 \pm 15~\mathrm{nm}$66, whereas the measured $55 \pm 15~\mathrm{nm}$67 reflects QD-to-waveguide misalignment, InP-to-Si misalignment, taper-tip imperfections, waveguide roughness, and possible non-radiative recombination (Burakowski et al., 2023).

Transport studies reveal a different aspect of the InAs/InP platform: exceptionally controlled tunnel barriers. In one axial nanowire device, the tunnel couplings evolve from $55 \pm 15~\mathrm{nm}$68 near depletion to $55 \pm 15~\mathrm{nm}$69 at high back-gate voltage, with near-symmetric barriers $55 \pm 15~\mathrm{nm}$70 below $55 \pm 15~\mathrm{nm}$71, charging energy $55 \pm 15~\mathrm{nm}$72, and barrier height $55 \pm 15~\mathrm{nm}$73. The gate dependence is quantitatively described by a double-rectangular-barrier WKB model (Thomas et al., 2019).

The same nanowire heterostructures support thermoelectric functionality. In strongly confined InAs/InP nanowire dots at $55 \pm 15~\mathrm{nm}$74, fitting conductance and thermopower with a two-spin-degenerate-level master-equation model yields an electronic figure of merit $55 \pm 15~\mathrm{nm}$75, maximum electrical power $55 \pm 15~\mathrm{nm}$76, and $55 \pm 15~\mathrm{nm}$77, close to the Curzon–Ahlborn linear-response limit (Prete et al., 2019). Off-resonant microwave driving of hard-wall InAs/InP nanowire dots produces Coulomb-diamond broadening, multiple current polarity reversals, and effective voltage fluctuations that are well described by time-averaging the static $55 \pm 15~\mathrm{nm}$78 characteristics (Cornia et al., 2019).

Not all device modifications are beneficial. A bottom InP/InGaAlAs DBR can improve extraction, but it can also mediate an unwanted excitation channel. In a C-band planar structure with a 25-pair InP/InGaAlAs DBR beneath the QD layer, photoluminescence excitation directly proves transfer of carriers from the DBR into the dots. The valence-band alignment favors holes, the energy difference between the InGaAlAs valence band edge and the lowest heavy-hole QD state is $55 \pm 15~\mathrm{nm}$79, and native InP defects act as stepping stones. Ensemble QD intensity then increases with temperature before quenching, with fitted $55 \pm 15~\mathrm{nm}$80 between $55 \pm 15~\mathrm{nm}$81 and $55 \pm 15~\mathrm{nm}$82, while the InGaAlAs-related emission around $55 \pm 15~\mathrm{nm}$83 decreases. The study emphasizes that this transfer can increase carrier relaxation times and thus be detrimental to coherence properties of single and entangled photons (Musiał et al., 2024).

This point generalizes a broader design principle already visible in selective-area and defect-rich structures: carrier reservoirs outside the dot can improve filling statistics under some conditions, but they also introduce timing jitter, charge imbalance, and spectral instability. In the DBR-mediated case the imbalance specifically favors holes and predisposes the dots to charged exciton formation; in selective-area droplet-epitaxy samples around $55 \pm 15~\mathrm{nm}$84, barrier-localized density of states causes slow rise times and strong thermal quenching without major temperature dependence of the decay times (Musiał et al., 2024, Shikin et al., 2018).

In aggregate, the InAs/InP quantum-dot family spans a broad design space: highly symmetric droplet-epitaxy dots for low anisotropy, self-assembled C-band dots for spin-photon interfaces, nanowire heterostructures for transport and thermoelectric studies, and heterogeneously integrated photonic devices for silicon-compatible routing. The central engineering tension is equally broad: the same band alignments, barrier layers, and auxiliary photonic structures that enable telecom operation, extraction, and integration also define the dominant non-radiative, charge-transfer, and dephasing pathways that limit ultimate quantum performance (Ha et al., 2016, Wasiluk et al., 11 Jul 2025, Burakowski et al., 2023, Musiał et al., 2024).