Non-exponential capture of electrons in GaAs with embedded InAs quantum dots

Walther, C.; Bollmann, J.; Kissel, H.; Kirmse, H.; Neumann, Wolfgang; Masselink, W. T.

doi:10.1016/s0921-4526(99)00604-3

Cited by 21 publications

(12 citation statements)

References 16 publications

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“…The first factor is related to the 7% lattice mismatch between InAs and GaAs, which induces the formation of self-assembled quantum dots (SAQD) when the InAs coverage is higher than the critical value of 1.65ML. The strained GaAs layer might result in the presence of deep levels, as have been previously reported [4][5][6]. The second factor is the growth temperature.…”

Section: Discussionmentioning

confidence: 75%

“…The 2D free carrier density is of n type and temperature dependent measurements give activation energies between 0.4 eV and 0.6 eV. These values are too high to be related to an electronic state of InAs QDs, which are in the order of 0.2eV [3,4]. …”

Section: Resultsmentioning

confidence: 94%

“…It is well known that stacking another InAs layer closer to a first one induces the formation of vertically coupled quantum dots [8]. However, recent works [4][5] indicate another effect of stacking layers, the reduction of the formation of deep levels by lattice relaxation.…”

Section: Discussionmentioning

confidence: 99%

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Hall effect in InAs/GaAs superlattices with quantum dots: identifying the presence of deep level defects

et al. 2004

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We have carried out van der Pauw resistivity and Hall effect measurements on a series of Molecular Beam Epitaxy InAs/GaAs superlattice samples containing InAs quantum dots. Three growth parameters were varied, the InAs coverage, the number of repetitions of the InAs/GaAs layers, and the GaAs spacer thickness. The results can be grouped in two sets, those samples presenting low and high resistivity. The group presenting low resistivity is composed by the samples with GaAs spacer of 30 monolayers (ML) and InAs coverage of 1.9 monolayers. The group presenting high resistivity is composed of samples with GaAs spacer of 40 ML. We claim that the high resistivity characteristic is due to the presence of deep level. Increasing the spacer from 30 to 40 ML decouples the InAs planes favouring the deep level formation.

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Section: Discussionmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 94%

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Hall effect in InAs/GaAs superlattices with quantum dots: identifying the presence of deep level defects

et al. 2004

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“…Previously it has been found that misfit dislocations at InGaAs/GaAs interfaces introduce hole traps [5]. Besides, native defects such as As and Ga vacancies, antisites and their complexes were discovered at InAs/GaAs, InGaAs/GaAs QD [6][7][8] and QW [9][10][11] interfaces, sometimes in combination with in-plane dislocations. In particular, Zhang et al found As and Ga vacancy clusters residing in the immediate vicinity of a QD to be efficient electron traps [9].…”

Section: Introductionmentioning

confidence: 99%

Carrier recombination in aligned InAs/GaAs quantum dots grown on strain‐relaxed InGaAs layers

Siegert

Marcinkevičius

Gaarder

et al. 2003

phys. stat. sol. (c)

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Alignment of InAs quantum dots was achieved by introducing misfit dislocations in a metastable InGaAs layer and subsequent annealing. Photoexcited carrier dynamics were studied using time-resolved photoluminescence. Comparison with control "non-aligned" InAs quantum dots show remarkable differences in integrated photoluminescence intensities with excitation power and photoluminescence decay time dependences on excitation intensities. Low-temperature carrier lifetimes were found to be below one hundred picoseconds for the aligned quantum dots and to be determined by non-radiative recombination processes. Samples with different barrier thicknesses between the InGaAs and the quantum dot layer allow the discussion of possible influences of carrier traps at InGaAs/GaAs interface and in the dot layer.1 Introduction Ordering of semiconductor quantum dots (QD) offers new functions for QD-based devices, such as single-electron transistors or highly parallel computing architectures. While the vertical correlation between quantum dot layers can be nearly perfect, lateral quantum dot alignment achieved during the self-assembly process is much less pronounced. One of the ways to form highly ordered patterns of QDs is to produce them on misfit dislocations, deliberately introduced into the structure [1,2]. During such growth, a square pattern of misfit dislocations is transferred into well-separated rows of sharply aligned quantum dots. However, dislocations may also have a negative effect introducing nonradiative recombination centres and reducing carrier lifetimes. In the present work we address this aspect of ordered quantum dot structures by studying photoexcited carrier dynamics by means of time-resolved photoluminescence (PL).

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“…Different epitaxial structures containing InAs QDs in GaAs were investigated in several works [1][2][3][4]. The measurements often show nonexponential decays [5] and metastable properties [6], which is explained by the different epitaxial structures and by quantum mechanical effects. Our earlier investigations have shown that the growth of InAs QDs generates point defects, which largely influence the current-voltage (I-V) and the capacitancevoltage (C-V) characteristics.…”

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confidence: 99%

Investigation of defects created by growth of InAs quantum dots in GaAs

Dózsa

Horváth

Hubı́k

et al. 2003

phys. stat. sol. (c)

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Defects created by self-organized InAs quantum dot growth in a GaAs matrix were investigated. Growth of the quantum dots was found to enhance strongly the tendency towards inhomogeneous growth. The inhomogeneity seems to stem from point defect clusters generated in the vicinity of a molecular beam epitaxy (MBE)/atomic layer MBE (ALMBE) interface. The point defects identified are characteristic of MBE and ALMBE GaAs layers. The InAs quantum dot states and interface states are not clearly detected since they are located in a depleted layer surrounding the point defects clusters.Introduction InAs quantum dots (QDs) in a GaAs matrix are one of the main model systems for growing nanoscale devices by the self-organizing growth techniques. Different epitaxial structures containing InAs QDs in GaAs were investigated in several works [1][2][3][4]. The measurements often show nonexponential decays [5] and metastable properties [6], which is explained by the different epitaxial structures and by quantum mechanical effects. Our earlier investigations have shown that the growth of InAs QDs generates point defects, which largely influence the current-voltage (I-V) and the capacitancevoltage (C-V) characteristics. The InAs QD quantum states were not clearly identified by deep level transient spectroscopy (DLTS) [7,8]. Fast defect transient (FDT) measurements in the QD samples revealed a series RC component of the capacitance transients [7,8]. The QDs were found to cause current instabilities at low temperature, due to metastable charge states located near the QD plane [9]. These metastable charge states seem to originate from free carriers captured by deep level defects near the QD plane, so an understanding of point defect generation by the QD growth is vital.In this work the defects in different GaAs/InAs/GaAs samples are investigated by C-V, DLTS, and FDT measurements. The samples are imaged by transmission electron microscopy (TEM). A model of a development of the space charge region with applied bias is suggested which explains the observed phenomena. An evaluation method of the C -V measurements is given to check the validity of this model.

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Non-exponential capture of electrons in GaAs with embedded InAs quantum dots

Cited by 21 publications

References 16 publications

Hall effect in InAs/GaAs superlattices with quantum dots: identifying the presence of deep level defects

Hall effect in InAs/GaAs superlattices with quantum dots: identifying the presence of deep level defects

Carrier recombination in aligned InAs/GaAs quantum dots grown on strain‐relaxed InGaAs layers

Investigation of defects created by growth of InAs quantum dots in GaAs

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