Search query: site-controlled quantum dot atomic force microscope

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abstract: An atomic force microscope assisted technique is developed to control the position and size of self assembled semiconductor quantum dots (QDs) Presently, the site precision is as good as 1.5 nm and the size fluctuation is within 5% with the minimum controllable lateral diameter of 20 nm. With the ability of producing tightly packed and differently sized QDs, sophisticated QD arrays can be controllably fabricated for the application in quantum computing. The optical quality of such site controlled QDs is found comparable to some conventionally self assembled semiconductor QDs. The single dot photoluminescence of site controlled InAs/InP QDs is studied in detail, presenting the prospect to utilize them in quantum communication as precisely controlled single photon emitters working at telecommunication bands.
author_names: H -Z Song

Tatsuya Usuki

Toshio Ohshima

Yoshiki Sakuma

Mitsuo Kawabe

Yositaka Okada

Kazuya Takemoto

Toshiyuki Miyazawa

Shinichi Hirose

Yoshiaki Nakata

Motomu Takatsu

Naoki Yokoyama
title: Site controlled quantum dots fabricated using an atomic force microscope assisted technique
venue: Nanoscale Research Letters
year: 2006

abstract: In this project, we combine Ga+ focused ion beam (FIB) patterning and self assembly of InGaAs quantum dots in order to produce regular quantum dot (QD) arrays. The GaAs substrate is patterned before transporting into molecular beam epitaxy growth chamber to do anneal and overgrowth. The thickness of deposited InAs is precisely controlled. Quantum dots are expected to nucleate at specific locations, where the ion beam has previously implanted gallium atoms. The properties of the quantum dots formed are related to the FIB beam parameters, which include accelerating voltage, probe current, dwell time and pitch. We studied and statistically analyzed the relationship, focusing on their diameter, height and distribution. Scanning electronic microscope (SEM) and atomic force microscope (AFM) images have been used to analyze the patterns and QDs before and after overgrowth. Micro PL study was performed to test the QD opto electronic property. Scanning transmission electron microscope (STEM) cross sectional analysis and X ray mapping is performed.
author_names: Haoyu Zhang

Ian M Ross

Thomas Walther
title: Study of site controlled quantum dot formation on focused ion beam patterned GaAs substrate
year: 2013

abstract: We have developed a nanoprobe assisted bottom up technique that allows to fabricate site controlled quantum dots (SC QDs) using a specially designed atomic force microscope probe, referred to as the Nano Jet Probe (NJP) Beginning with the fabrication of regular QD arrays by using the NJP, we vertically aligned self assembled InAs QDs using the strain induced stacking method and produced assembled QD stacks. In order to improve the optical property of the SC QDs, an AlGaAs barrier layer was introduced in the spacer layer of the stacked structures. The photoluminescence measurements of the fabricated structures revealed that they had good crystallographic qualities.
author_names: Shunsuke Ohkouchi

Nobuhiko Ozaki

Yoshimasa Sugimoto

Hiroshi Ishikawa

Kiyoshi Asakawa
title: Site controlled InAs quantum dot formation grown on the templates fabricated by the Nano Jet Probe method
year: 2009

abstract: In this work, surface modification of InAs wetting layer was carried out during InAs/GaAs (001) quantum dot molecular beam epitaxy growth by in situ pulsed laser (355 nm/ 10 ns) We investigated the morphology transformation of wetting layer by atomic force microscope. Atomic layer removal and formation of nano holes were observed on the sample surface. It is proposed that the material removal of wetting layer induced by electronic excitation is triggered by In atom vacancies due to the desorption at substrate temperature of 480degC. The effects of surface modification on QD growth were studied by subsequent InAs deposition after laser irradiation. Preferential nucleation in nano holes were found in the experiments. This study provides a novel technique leading to site controlled to InAs/GaAs (001) QDs fabrication.
author_names: C Chen

Linyun Yang

Changwei Deng

Xinning Yang

Lili Miao

Zhenwu Shi

Changsi Peng
title: Surface modification on InAs wetting layer by in situ pulsed laser and the effets on quantum dot growth
venue: Other Conferences
year: 2018

abstract: We have demonstrated the selective area growth of self assembled InAs quantum dots (QDs) in the desired regions by using a template composed of InAs QD arrays. These InAs QDs were fabricated by the use of a specially designed atomic force microscope cantilever, referred to as the Nano Jet Probe (NJP) Using the NJP, two dimensional arrays of ordered In nano dots were fabricated in the selected square regions on a GaAs substrate and directly converted to InAs QD arrays by subsequent annealing by the irradiation of As flux. By using the converted QD arrays as strain templates, self organized InAs QDs were formed in the selected square regions. These InAs QD arrays were used for the further stacking of QDs, and photoluminescence emission was confirmed from the fabricated stacked QD structure.
author_names: Shunsuke Ohkouchi

Yoshimasa Sugimoto

Nobuhiko Ozaki

Hiroshi Ishikawa

Kiyoshi Asakawa
title: Molecular beam epitaxial growth of site controlled InAs quantum dot arrays using templates fabricated by the Nano Jet Probe method
year: 2008

abstract: We have fabricated GaAs oxides by using atomic force microscope (AFM) assisted anodic oxidation at various bias voltages, Vox, and studied their chemical compositions and thermal stabilities. The oxides grown at bias voltages less than 30 V desorbed after standard thermal cleaning in molecular beam epitaxy, while the oxide patterns fabricated at Vox>=40 V survived on the surface. We have further investigated the chemical composition of the oxides by X ray photoemission spectroscopy. It has been found that the AFM oxides grown at Vox~10 V predominantly consist of Ga2O and GaO, whereas those grown at Vox~50 V contain a Ga2O3 component. This result indicates that the better thermal stability of AFM oxides grown at Vox>=40 V can be attributed to the formation of Ga2O3. We grew a GaAs buffer layer on the oxide nanomasks and obtained nanoholes. After supplying InAs, selective dot nucleation took place in the nanoholes, resulting in successful formation of site controlled QDs.
author_names: Kyu Man Cha

Kenji Shibata

Isao Horiuchi

Masao Kamiko

Ryoichi Yamamoto

Kazuhiko Hirakawa
title: Chemical composition and thermal stability of GaAs oxides grown by AFM anodic oxidation for site controlled growth of InAs quantum dots
year: 2011

abstract: We have successfully fabricated high density two dimensional indium (In) nano dot arrays on a GaAs substrate with periods of 50 nm. These nano dot structures were formed using an atomic force microscope (AFM) probe with a specially designed cantilever (the Nano Jet Probe) having a hollow pyramidal tip with a sub micron size aperture on the apex and an In reservoir tank within the stylus. These ordered In nano dot arrays can be directly converted to InAs quantum dot (QD) arrays by subsequent irradiation of arsenic flux in the molecular beam epitaxy chamber, which is connected to the AFM chamber through an ultra high vacuum (UHV) tunnel.
author_names: Shunsuke Ohkouchi

Y Nakamura

Hitoshi Nakamura

Kiyoshi Asakawa
title: Indium nano dot arrays formed by field induced deposition with a Nano Jet Probe for site controlled InAs/GaAs quantum dots
year: 2004

abstract: Abstract We have successfully and reproducibly fabricated uniform indium (In) nano dots at a selected point. Nano dot formation was realized using an atomic force microscope (AFM) probe with a specially designed cantilever, which was equipped with a hollow pyramidal tip with a sub micron size aperture on the apex and an In reservoir tank within the stylus. The In nano dots formed in this study can be directly converted to InAs quantum dots by subsequent irradiation of arsenic flux in the molecular beam epitaxy chamber, which is connected to the AFM chamber through an ultra high vacuum tunnel.
author_names: Shunsuke Ohkouchi

Y Nakamura

Hitoshi Nakamura

Kiyoshi Asakawa
title: Nano probe assisted technology of indium nano dot formation for site controlled InAs/GaAs quantum dots
year: 2004

abstract: We propose a new nano probe assisted technique which enables the formation of site controlled InAs quantum dots (QDs) High density two dimensional indium (In) nano dot arrays on a GaAs substrate were fabricated by using a specially designed atomic force microscope (AFM) probe (the Nano Jet Probe) This developed probe has a hollow pyramidal tip with a sub micron size aperture on the apex and an In reservoir tank within the stylus. By applying a voltage pulse between the pyramidal tip and the sample, In clusters were extracted from the reservoir tank within the stylus through the aperture, resulting in the In nano dot formation. These In nano dots can be directly converted to InAs QD arrays by subsequent irradiation of arsenic flux.
author_names: Shunsuke Ohkouchi

Yusui Nakamura

Hitoshi Nakamura

Kiyoshi Asakawa
title: Site control technology for InAs quantum dot formation by direct deposition of indium nano dots with a nano jet probe
year: 2003

abstract: We havedemonstrated theselective areagrowth ofhighdensity InAsquantum dots (QDs)inthesquare regions byusing site controlled InAsdots that wereformed inthedesired regions astemplates. These fabricated InAsdots forthetemplates wereenabled bytheuseofa specially designed atomic force microscope (AFM)cantilever, referred toastheNano Jet Probe(NJP) UsingtheNJP,two dimensional (2D)arrays ofordered Innano dots were fabricated inthedesired square regions onaGaAssubstrate. These Innano dots weredirectly converted toInAsQD arrays bysubsequent annealing withirradiation ofarsenic flux. Byusing theconverted QD arrays asstrain templates, self organized InAsQDswithhighdensity were formed intheselected square regions.
author_names: Shunsuke Ohkouchi

Yoshimasa Sugimoto

Nobuhiko Ozaki

Hiroshi Ishikawa
title: SELECTIVEFORMATION OFHIGH DENSITYInAs QUANTUM DOT ARRAYS USINGTEMPLATES FABRICATEDBYTHE NANO JETPROBE
year: 2007