Optical and electronic properties of low-density InAs/InP quantum-dot-like structures designed for single-photon emitters at telecom wavelengths

Abstract

Due to their band-structure and optical properties, InAs/InP quantum dots (QDs) constitute a promising system for single-photon generation at the third telecom window of silica fibers and for applications in quantum communication networks. However, obtaining the necessary low in-plane density of emitters remains a challenge. Such structures are also still less explored than their InAs/GaAs counterparts regarding optical properties of confined carriers. Here, we report on the growth via metal-organic vapor phase epitaxy and investigation of low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7 μm, which includes the S, C, and L bands of the third optical window. We observe multiple photoluminescence (PL) peaks originating from flat QDs with the height of a few material monolayers. Temperature-dependent PL reveals a redistribution of carriers between families of QDs. Via time-resolved PL, we obtain radiative lifetimes nearly independent of emission energy in contrast to previous reports on InAs/InP QDs, which we attribute to strongly height-dependent electron-hole correlations. Additionally, we observe neutral and charged exciton emission from spatially isolated emitters. Using the eight-band k•p model and configuration-interaction method, we successfully reproduce the energies of emission lines, the dispersion of exciton lifetimes, the carrier activation energies, as well as the biexciton binding energy, which allows for a detailed and comprehensive analysis of the underlying physics.

Optical Properties of Site-Selectively Grown InAs/InP Quantum Dots with Predefined Positioning by Block Copolymer Lithography

“…The temperature shift of PL modes A–F follow the bandgap evolution of QD material quite nicely except the mode A’. This observation is in contrast to the previously observed temperature-driven PL modes evolution in multimodal-distributed SK InAs/InP QDs, where the PL band energy deviated from the predicted bandgap shift [ 1 ]. The deviation, particularly at elevated temperatures, is mainly governed by a carrier redistribution process between different families of dots and among QDs of an individual family, shifting the mean energy of related PL mode either upward (due to the filling of large dots within the distribution), or downward (due to the carrier escape from higher to lower energy dots) [ 48 ].…”

“…In the case of SK InAs/InP QDs, the carrier transfer can happen through either: (i) lateral coupling, namely carrier tunneling between QD excited states in their dense ensemble [ 49 , 50 ]; (ii) hybrid QD-WL states [ 51 , 52 ]; (iii) indirect transitions between the WL and QD energy levels [ 53 , 54 ]; (iv) carrier re-excitation to the WL or barrier material due to the rising phonon bath, and subsequent redistribution among QDs with higher confinement energy [ 1 ]. Accordingly, the lack of the PL mode energy deviation for the studied QDs concentrated in A–F distributions suggests the absence of direct coupling between the dots and an inefficient mutual carrier exchange which could be mediated only through the barrier states due to the absence of a WL.…”

“…Self-assembled semiconductor InAs quantum dots (QDs) grown on a standard InP(100) substrate are prospective candidates for an active part of optoelectronic devices. The InAs/InP QD material composition in line with the quasi-0D density of states [ 1 , 2 ] and relatively strong carrier confinement [ 1 , 2 , 3 ] make these QDs attractive for lasers and optical amplifiers operating in the near-infrared spectral range above , important for telecom applications [ 4 , 5 , 6 , 7 ]. Despite the successful realization of InAs/InP QDs-based lasers and optical amplifiers [ 4 , 5 , 8 , 9 , 10 ], their parameters are still far from expected [ 11 , 12 ].…”

Оптические свойства трехмерных островков InGaP(As), сформированных методом замещения элементов пятой группы

“…В настоящее время усилия многих исследовательских групп направлены на поиск методов формирования полупроводниковых квантовых точек низкой плотности, которые могут эффективно использоваться в качестве активной среды однофотонных излучателей для таких приложений как квантовая криптография [1][2][3], для различных схем квантовых вычислений [4][5], а также прецизионных измерений [6,7]. Разработаны различные технологические режимы эпитаксиального роста самоорганизующихся КТ или последующего отжига структуры, позволившие уменьшить плотность КТ InAs/InP до < 10 9 cm −2 [8], КТ InAs/InGaAsP/InP (100) до 1.3 • 10 9 cm −2 [9], КТ CdTe до 10 7 −10 8 cm −2 [10]. Также для создания КТ низкой плотности, применяется более сложный метод формирования с использованием ростовой поверхности предустановленной морфологии (site-controlled epitaxy) [11,12].…”

“…Недавно в работе [13] был предложен новый способ формирования полупроводниковых трехмерных островков при замещении фосфора на мышьяк в тонком слое InGaP (толщиной менее 3 nm) с использованием подложек GaAs. В этом случае на поверхности GaAs фор-мируются трехмерные островки InGaPAs/GaAs овальной формы, низкой плотности (∼ 1.3 • 10 10 cm −2 ), вытянутые вдоль направления [1][2][3][4][5][6][7][8][9][10] и излучающие в спектральном диапазоне вблизи 1 µm при комнатной температуре.…”