Many-particle effects in Ge quantum dots investigated by time-resolved capacitance spectroscopy

Kapteyn, C. M. A.; Lion, M.; Heitz, R.; Bimberg, D.; Miesner, C.; Asperger, T.; Βrunner, Karl; Abstreiter, G.

doi:10.1063/1.1334651

Cited by 52 publications

(36 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4b. A similar behaviour has previously been observed in Ge/Si QDs [10]. For a reverse bias of 9.3 V an activation energy of 400 meV is determined.…”

supporting

confidence: 60%

“…In order to investigate the electronic properties and the carrier dynamics in QD systems, capacitance spectroscopy has been demonstrated to be a feasible tool [5]. Previously, we have employed deep level transient spectroscopy (DLTS) [6] and admittance spectroscopy to study InAs/GaAs [7][8][9] and Ge/Si QDs [10]. QD formation in the latter material system, however, typically leads to rather large islands and low area densities, which renders it considerably less attractive.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Hole storage in GaSb/GaAs quantum dots for memory devices

Geller¹,

Kapteyn

Müller‐Kirsch

et al. 2003

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

The hole confinement of self-organized GaSb/GaAs quantum dots embedded in n + p-diodes is investigated experimentally by admittance spectroscopy. The highest thermal activation energy obtained, 400 meV, refers to only weakly charged quantum dots. Detailed bias-dependent investigations allow to study state-filling and Coulomb charging effects. State filling lowers the activation energy down to 150 meV in quantum dots charged with the maximum number of about 15 holes. The observed thermal activation barrier for GaSb/GaAs quantum dots is about twice as high as for structurally comparable InAs/GaAs quantum dots.The ultimate non-volatile electronic memory cell confines a single carrier to represent a bit of information [1]. As conventional material processing technology is not yet able to manufacture suitable semiconductor structures, self-organized quantum dots (QDs) offer an elegant method to create huge ensembles of electronic traps for single or very few carriers [2]. So far, mainly the applicability of InAs/GaAs QDs for memory concepts has been studied, see e.g. Refs. [3,4]. A crucial parameter for memory operation is the thermal activation barrier for the trapped carriers -the larger it is, the longer the storage time becomes. In order to investigate the electronic properties and the carrier dynamics in QD systems, capacitance spectroscopy has been demonstrated to be a feasible tool [5]. Previously, we have employed deep level transient spectroscopy (DLTS) [6] and admittance spectroscopy to study InAs/GaAs [7][8][9] and Ge/Si QDs [10]. QD formation in the latter material system, however, typically leads to rather large islands and low area densities, which renders it considerably less attractive. InAs/GaAs QDs, on the other hand, typically exhibit electron and hole ground state localisation energies in the order of up to about 200 meV. GaSb/GaAs QDs have similar structural properties as typical InAs/GaAs QDs, but a significantly larger hole ground state localization energy is expected due to the type-II band alignment attractive for holes [11]. Here, we study the thermal activation barrier of hole-charged GaSb/GaAs QDs by admittance spectroscopy for varying filling conditions. The layer structure of the investigated GaSb QD sample, grown by metal organic chemical vapor deposition [12,13], is schematically depicted in Fig. 1a. A 500 nm thick highly p-doped contact layer (p = 1 × 10 18 cm -3 ) and a 700 nm thick p-doped GaAs layer (p = 3 × 10 16 cm -3) were deposited on top of a semi-insulating GaAs substrate. Subsequently, a layer of GaSb QDs (2.8 ML nominally) was created in the Stranski-Krastanow growth mode. The QD layer is sandwiched between two 10 nm thick undoped GaAs spacers, and followed by 500 nm p-doped GaAs (p = 3 × 10 16 cm -3 ). Finally, 400 nm of highly ndoped GaAs (n = 7 × 10 17 cm -3 ) was deposited in order to form a n + p diode structure. Employing standard optical lithography and chemical wet-etching, mesa structures with a diameter of 800 µm were created. Standard Ohmic contacts were formed on...

show abstract

“…4b. A similar behaviour has previously been observed in Ge/Si QDs [10]. For a reverse bias of 9.3 V an activation energy of 400 meV is determined.…”

supporting

confidence: 60%

mentioning

confidence: 99%

Hole storage in GaSb/GaAs quantum dots for memory devices

Geller¹,

Kapteyn

Müller‐Kirsch

et al. 2003

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

show abstract

“…Hence the DLTS peak is broadened. 18,32 The activation energy derived from the Arrhenius plot represents the mean activation energy for all hole levels of the QD ensemble including the additional Al 0.1 Ga 0.9 As barrier. If we assume a value of E V B = 54 meV for the valence band offset (based on a 66:34 split of the band gap difference 33 ) between GaAs and Al 0.1 Ga 0.9 As and subtract this value from the data, we get a mean activation energy of ∼466 meV for the QD ensemble.…”

Section: B Conventional Dltsmentioning

confidence: 99%

Linking structural and electronic properties of high-purity self-assembled GaSb/GaAs quantum dots

et al. 2012

Self Cite

View full text Add to dashboard Cite

Hayne, M. (2012). Linking structural and electronic properties of high-purity self-assembled GaSb/GaAs quantum dots. Physical Review B, 86(3) Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policyIf you believe that this document breaches copyright please contact us at: openaccess@tue.nl providing details and we will investigate your claim. We present structural, electrical, and theoretical investigations of self-assembled type-II GaSb/GaAs quantum dots (QDs) grown by molecular beam epitaxy. Using cross-sectional scanning tunneling microscopy (X-STM) the morphology of the QDs is determined. The QDs are of high purity (∼100% GaSb content) and have most likely the shape of a truncated pyramid. The average heights of the QDs are 4-6 nm with average base lengths between 9 and 14 nm. Samples with a QD layer embedded into a pn-diode structure are studied with deep-level transient spectroscopy (DLTS), yielding a hole localization energy in the QDs of 609 meV. Based on the X-STM results the electronic structure of the QDs is calculated using 8-band k·p theory. The theoretical localization energies are found to be in good agreement with the DLTS results. Our results also allow us to estimate how variations in size and shape of the dots influence the hole localization energy.

show abstract

“…Authors of main part of papers present experimental results of the investigation of the C-V dependences for structures with QDs layers and determination such parameters of QDs, as concentration, energetic position and capture cross-section. They discussed considerably widespread peculiarities of C-V dependences of the Schottky structures with well-known shelf in such dependences connected with charge accumulation in QDs states [3][4][5][6] . A number of authors proposed some methods for the detail calculation of the capacitance and compared experimental and theoretical results [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

“…Because of the new abilities to accumulate the carriers of a charge in the QDs which could built into various semiconductor heterojunctions such structures are capable to show the certain physical phenomenon connected with charge of QDs and reveal some specific features in capacitance-voltage (C-V) dependences [1][2][3][4][5][6] . Authors of main part of papers present experimental results of the investigation of the C-V dependences for structures with QDs layers and determination such parameters of QDs, as concentration, energetic position and capture cross-section.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Negative Differential Capacitance-Voltage Dependences of Shottky Diode Structures With Gaas/Inas QDS

Lin

Lee

Ilchenko

et al. 2014

SEMST

View full text Add to dashboard Cite

Ñapacitance-voltage investigations were made on Schottky diodes with embedded GaAs/InAs quantum dots and quantum wells. An effect of the negative differential capacitance(NDC) was clear observed. Numerical modeling of the C-V dependences was carried out with temperature and concentration of QDs as parameters. Energy structure of the investigated samples was examined by deep level transient spectroscopy(DLTS). It was shown that the proposed model is in good agreement with experiment and describes well the NDC effect.

show abstract

Many-particle effects in Ge quantum dots investigated by time-resolved capacitance spectroscopy

Cited by 52 publications

References 20 publications

Hole storage in GaSb/GaAs quantum dots for memory devices

Hole storage in GaSb/GaAs quantum dots for memory devices

Linking structural and electronic properties of high-purity self-assembled GaSb/GaAs quantum dots

Investigation of Negative Differential Capacitance-Voltage Dependences of Shottky Diode Structures With Gaas/Inas QDS

Contact Info

Product

Resources

About