Photoreflectance-probed excited states in InAs∕InGaAlAs quantum dashes grown on InP substrate

Rudno‐Rudziński, W.; Kudrawiec, R.; Podemski, P.; Sęk, G.; Misiewicz, J.; Somers, A.; Schwertberger, R.; Reithmaier, J.P.; Forchel, A.

doi:10.1063/1.2226503

Cited by 42 publications

(36 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar temperature dependent carrier dynamics was also carried out by Jahan et al [194] on InAs/InAlAs Qdash heterostructure. Using PL and photo-reflectance (PR) measurements on a single Qdash layer embedded in InGaAlAs buffer layers, Rudno-Rudzinski et al showed the existence of ~2 ML thick wetting layer [195], observed the presence of ES at an energy of ~150 meV above the GS transition in Qdashes [196], and studied the interband optical transitions in DaWELL structure with InGaAs/InGaAlAs Qwells [197]. In addition, Podemski et al investigated the efficiency of excitons and free carrier injections in Qdash tunnel-injection structures via PL measurements [198] and measured Qwell-Qdash energy transfer up to 130 K employing PL excitation (PLE) study [199].…”

Section: Qdash Optical Propertiesmentioning

confidence: 99%

Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

Khan

Ooi

2014

Progress in Quantum Electronics

View full text Add to dashboard Cite

The advances in lasers, electronic and photonic integrated circuits (EPIC), optical interconnects as well as the modulation techniques allow the present day society to embrace the convenience of broadband, high speed internet and mobile network connectivity. However, the steep increase in energy demand and bandwidth requirement calls for further innovation in ultra-compact EPIC technologies. In the optical domain, innovation in the laser technologies beyond the current quantum well (Qwell) based laser technologies are already taking place and presenting very promising results. Homogeneously grown quantum dot (Qdot) lasers, can serve in the future energy saving information and communication technologies (ICT) as the work-horse for transmitting information through optical fiber. The encouraging results in the zero-dimensional (0D) structures emitting at 980 nm, in the form of vertical cavity surface emitting laser (VCSEL), are already operational at low threshold current density and capable of 40 Gbps error-free transmission at 108 fJ/bit. Eventual achievements for lasers operating in the O-, C-, L-, U-bands, and beyond will eventually lay the foundation for green ICT. On the hand, the inhomogeneously grown quasi 0D quantum dash (Qdash) lasers are brilliant solutions for potential broadband connectivity in server farms or access network. A single broadband Qdash laser operating in the stimulated emission mode can replace tens of discrete narrow-band lasers in dense wavelength division multiplexing (DWDM) transmission thereby further saving energy, cost and footprint. In this article, we review the progress of both Qdots and Qdash devices based on the InAs/InGaAlAs/InP and InAs/InGaAsP/InP material systems, from the angles of growth and device performance.2

show abstract

Section: Qdash Optical Propertiesmentioning

confidence: 99%

Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

Khan

Ooi

2014

Progress in Quantum Electronics

View full text Add to dashboard Cite

show abstract

“…To emphasize the influence of confinement potential depth on the polarization properties of emission, we have compared the investigated structures with other elongated nanostructures-InAs/InGaAlAs/InP QDashes (LAR exceeding 5) [42][43][44][45]. Such InP-based structures exhibit much deeper confinement potential for both types of carriers, i.e., by definition expected to be much less sensitive to the peculiarities of the confining potential shape.…”

Section: A Degree Of Linear Polarization Of the Surface Emissionmentioning

confidence: 99%

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

et al. 2014

Self Cite

View full text Add to dashboard Cite

In this paper we present a comprehensive and detailed analysis of carrier/exciton wave function extension in large low-strain In 0.3 Ga 0.7 As quantum dots (QDs). They exhibit rather shallow confinement potential with electron/hole localization energy below 30 meV and confinement strength substantially weakened in comparison to typical epitaxial quasi-zero-dimensional semiconductor nanostructures. The aim of this study is to investigate the influence of different factors on the wave function (probability density distribution) for carriers or excitons in this regime, i.e., object shape anisotropy as well as strain, piezoelectricity, and Coulomb interactions, and to identify the physical mechanisms determining the properties of optical emission. To probe the wave function symmetry, polarization-resolved photoluminescence has been performed, and the spatial extensions of the corresponding probability densities have been verified in magneto-optical measurements. The observed diamagnetic coefficients in the range of (15-31) μeV/T 2 reflect large in-plane QD size. These studies also enable us to investigate the importance of light hole states admixture to the valence band ground state in such nanostructures, which can be addressed via the degree of linear polarization of emission as well as the exciton g X factor. The linear-polarization-resolved measurements revealed an exceptionally low exciton fine structure splitting of 5 μeV on average as well as a low emission polarization degree of −0.05, with the polarization perpendicular to the QD elongation direction dominating. The increased light hole contribution to the lowest energy hole level is reflected in the decreased exciton g X factor (in the range of 0-1) and is consistent with the results of the eight-band k·p modelling. Based on the temperature dependence of the diamagnetic coefficient, the problem of individual QD uniformity has additionally been discussed. To evaluate the impact of the confinment potential and the structure geometry on the optical properties of the QDs, a comparison between the investigated dots and InAs/InGaAlAs/InP quantum dashes exhibiting a much deeper confining potential is presented.

show abstract

“…One can see only a very weak PR feature at the PL peak energy, which is common for the QDash-related signal due to a small total absorption of a single QDash layer and their large intrinsic nonuniformity. 36 In contrast, pronounced PR resonances can be identified for all the samples at higher energies, related to optical transitions within the mixture of 0D-2D DOS. The energy of these transitions increases with d well , resulting in the decreasing spectral detuning between QW and QDash parts.…”

mentioning

confidence: 91%

“…The photoreflectance (PR) measures the change in the reflectivity spectrum upon photo-modulation, resulting in a derivative-like response, with clear signatures of optical transitions. 36 The PR was performed at both T = 5 K and RT, however, at low temperature the PR signal (not shown) cannot be separated from the PL signal dominating the overall spectral response. At T=300 K, the PL process constitutes only a background of the pronounced PR amplitude.…”

mentioning

confidence: 99%

“…Growth details, as well as optical and electronic properties of such QDashes, are described in the previously published articles. [34][35][36] For photoluminescence (PL), photoluminescence excitation (PLE), and time-resolved photoluminescence experiments (TRPL), the samples were held in a continuous-flow liquid-helium cryostat at T = 5 K. In the PL experiment, the TI structures were excited above the InAlGaAs barrier by the 532 nm line from a neodymium-doped yttrium aluminum garnet laser. The resultant PL signal was dispersed by a 0.5-m-focal-length monochromator and measured with an InGaAs linear array detector.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 µm emission

et al. 2017

Self Cite

View full text Add to dashboard Cite

We have investigated optical properties of hybrid two-dimensional-zero-dimensional (2D-0D) tunnel structures containing strongly elongated InAs/InP(001) quantum dots (called quantum dashes), emitting at 1.55 μm. These quantum dashes (QDashes) are separated by a 2.3 nm-width barrier from an InGaAs quantum well (QW), lattice matched to InP. We have tailored quantum-mechanical coupling between the states confined in QDashes and a QW by changing the QW thickness. By combining modulation spectroscopy and photoluminescence excitation, we have determined the energies of all relevant optical transitions in the system and proven the carrier transfer from the QW to the QDashes, which is the fundamental requirement for the tunnel injection scheme. A transformation between 0D and mixed-type 2D-0D character of an electron and a hole confinement in the ground state of the hybrid system have been probed by time-resolved photoluminescence that revealed considerable changes in PL decay time with the QW width changes. The experimental discoveries have been explained by band structure calculations in the framework of the eight-band k⋅p model showing that they are driven by delocalization of the lowest energy hole state. The hole delocalization process from the 0D QDash confinement is unfavorable for optical devices based on such tunnel injection structures.

show abstract

Photoreflectance-probed excited states in InAs∕InGaAlAs quantum dashes grown on InP substrate

Cited by 42 publications

References 17 publications

Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 µm emission

Contact Info

Product

Resources

About