The effect of InAs quantum layer and quantum dots on the electrical characteristics of GaAs structures

Dózsa, L.; Horváth, Zs. J.; Tuyen, Vo Van; Pődör, B.; Mohácsy, T.; Franchi, Stefano; Frigeri, P.; Gombia, E.; Mosca, R.

doi:10.1016/s0167-9317(99)00469-4

Cited by 17 publications

(15 citation statements)

References 9 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: 73%

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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: 73%

“…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%

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

et al. 2004

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“…The DLT spectra were obtained using a Polaron S4600 DLTS system. The C-V measurements were performed in different set ups described elsewhere [7,8]. The FDT measurement is described in [12].…”

Section: /Cmmentioning

confidence: 99%

“…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].…”

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confidence: 99%

“…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].…”

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confidence: 99%

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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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Instability of electrical characteristics of GaAs/InAs quantum dot structures

Dózsa

Horváth

Gombia³

et al. 2005

phys. stat. sol. (c)

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PACS 71.55.Eq, 73.21.LaWe report on GaAs samples containing an InAs quantum dot matrix grown from 3 monolayers of InAs. In this case, most of the mechanical stress relaxes by misfit dislocations. Capacitance measurements have been performed on macroscopic devices and, also, from a scanning microscope in which the capacitance is measured between the probe and sample surface. It was found that the electrical characteristics dramatically change during the capacitance measurements. This is explained by a degradation of the quantum dot layer which is attributed to the generation of point defects and/or dislocations. These results draw attention to the fact that, at the microscopic scale measurement, a small current may result in a large local current density which, in turn, degrades the device.

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The effect of InAs quantum layer and quantum dots on the electrical characteristics of GaAs structures

Cited by 17 publications

References 9 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

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

Instability of electrical characteristics of GaAs/InAs quantum dot structures

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