A preprint dated 25 August 2026 reports that InGaAs quantum dots in AlGaAs nanowires showed emission shifting from approximately 780 to 920 nanometres across the reported dot-height designs. The work also describes separate individual nanowire demonstrations: one contained a 2-second and a 5-second InGaAs dot, while another combined a GaAs dot with a 5-second InGaAs dot. An InAs segment grown on AlGaAs was examined for structural and compositional compatibility, but the reported result was not an optical demonstration of a pure InAs quantum dot emitting in the telecom band.
How the emission was compared
The nanowires were wurtzite AlGaAs crystals grown by molecular beam epitaxy, with InGaAs insertions made during short interruptions of axial AlGaAs growth. In the two main designs, the insertion lasted 2 seconds or 5 seconds; the corresponding dots were approximately 5 nanometres and 10 nanometres high, respectively. The results compare these growth designs; they do not establish that insertion time alone caused the observed shift.
Macro-photoluminescence, a measurement of light emitted by the material, showed the shift from approximately 780 nanometres to approximately 920 nanometres. The measurements were performed at approximately 6 kelvin using a 532-nanometre continuous-wave laser.
Two emitters in one wire
One individual nanowire contained both a 2-second and a 5-second InGaAs quantum dot. Their emissions were distinct: 780 nanometres for the 2-second dot and 900 nanometres for the 5-second dot.
A separate individual nanowire used a mixed-composition design: a GaAs dot and a 5-second InGaAs dot. The GaAs dot was formed by turning off the aluminium flux for 17 seconds. The two dots were approximately 2 micrometres apart and emitted at 780 nanometres and 850 nanometres, respectively.
These paired-dot results were individual demonstrations, and the study does not report replication counts or quantified reproducibility for the structures.
A single-photon signal, with variation
Optical tests on representative dots found a second-order correlation, g2(0), close to zero. The study uses this result to describe single-photon behavior, and the reported exciton and charged-exciton lifetime was approximately 1 nanosecond. The overall number of optically characterized dots was not reported.
The reported optical response varied among the 5-second examples. A representative 5-second dot had an additional charged-biexciton transition and longer correlation times than the 2-second case, while some other 5-second dots showed faster dynamics.
The InAs result has a narrower scope
The InAs result was a materials-compatibility test rather than an optical quantum-dot demonstration. An InAs segment grown on an AlGaAs nanowire showed pure wurtzite structure and compositional purity, with no aluminium or gallium emission detected. It therefore does not show a pure InAs quantum dot emitting in the telecom band.
Crystal-phase insertions were reported to modulate quantum-dot emission wavelength without splitting the InGaAs quantum dot into multiple distinct emitters. Among twelve 5-second InGaAs quantum-dot examples, all had at least one crystal-phase insertion, and emission ranged from 820 nanometres to 930 nanometres.
EDX measurements of elemental composition on eight nanowires with a 5-second dot found an average In/(In+Ga) ratio of 0.40, with a standard deviation of 0.13.
What the demonstrations do not establish
Taken together, the direct demonstrations are InGaAs emission across growth designs, representative single-photon behavior, selected paired-dot structures, and structural and compositional compatibility between an InAs segment and AlGaAs.
The work does not show pure InAs quantum-dot emission or telecom operation. It also does not quantify replication or reproducibility for the paired-dot structures.
Publication status
The supplied document is an arXiv preprint, version 1, dated 25 August 2026.
Paper data and sources
Original title: AlGaAs nanowires as a universal platform for GaAs, InGaAs, and InAs quantum dots
Authors: Rohan Radhakrishnan, Rodion Reznik, Gilles Patriarche et al.
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-25
DOI: Not available
Original paper · Full text