نتایج جستجو برای: quantum dots qds

تعداد نتایج: 304238  

Journal: :Nano letters 2005
Jaakko Sormunen Juha Riikonen Marco Mattila Jouni Tiilikainen Markku Sopanen Harri Lipsanen

Transformation of self-assembled InAs quantum dots (QDs) on InP(100) into quantum rings (QRs) is studied. In contrast to the typical approach to III--V semiconductor QR growth, the QDs are not capped to form rings. Atomic force micrographs reveal a drastic change from InAs QDs into rings after a growth interruption in tertiarybutylphosphine ambient. Strain energy relief in the InAs QD is discus...

Journal: :Chemical communications 2014
Lun Pan Songbo Wang Ji-Jun Zou Zhen-Feng Huang Li Wang Xiangwen Zhang

V-doped TiO2 quantum dots (QDs) possessing many Ti(3+) defects were fabricated by simple hydrolysis using MCM-41 as a support. The QDs show high charge-separation efficiency and high photocatalytic activity due to the quantum size effect and the newly formed defect- and dopant-mediated band levels.

2012
Shaikh Ahmed Muhammad Usman Clemens Heitzinger Rajib Rahman Andrei Schliwa Gerhard Klimeck

Electrons and holes captured in self-assembled quantum dots (QDs) are subject to symmetry breaking that cannot be represented in with continuum material representations. Atomistic calculations reveal symmetry lowering due to effects of strain and piezo-electric fields. These effects are fundamentally based on the crystal topology in the quantum dots. This work studies these two competing effect...

Journal: :ACS nano 2012
Svetlana Kilina Kirill A Velizhanin Sergei Ivanov Oleg V Prezhdo Sergei Tretiak

Understanding the pathways of hot exciton relaxation in photoexcited semiconductor nanocrystals, also called quantum dots (QDs), is of paramount importance in multiple energy, electronics and biological applications. An important nonradiative relaxation channel originates from the nonadiabatic (NA) coupling of electronic degrees of freedom to nuclear vibrations, which in QDs depend on the confi...

Journal: :Optics letters 2003
Jia-Yu Zhang Xiao-Yong Wang Min Xiao Yong-Hong Ye

The angular dependence of the spontaneous emission of CdTe quantum dots (QDs) inside a photonic crystal with a pseudogap is reported. The sensitive dependences of the radiative lifetime and the photoluminescence spectrum of CdTe QDs on the observation angle demonstrate the effect of the photonic bandgap on the spontaneous emission of the QDs.

Journal: :Nano letters 2010
Vanessa Wood Matthew J Panzer Jean-Michel Caruge Jonathan E Halpert Moungi G Bawendi Vladimir Bulović

We report a novel unipolar light-emitting device architecture that operates using direct-current, field-driven electroluminescence of colloidally synthesized quantum dots (QDs). This device architecture, which is based only on transparent ceramics and QDs, enables emission from different color QDs and, for the first time, constant QD electroluminescence during extended operation in air, unpacka...

Journal: :Chemical communications 2015
Pinhua Rao Wei Yao Zhichun Li Long Kong Wenqi Zhang Liang Li

A simple approach was introduced to enhance the photostability of CuInS2@ZnS core@shell quantum dots (QDs) by doping aluminium into the ZnS shell. Aluminium in the as-prepared QDs was oxidized to Al2O3, which formed a passivation oxide layer that effectively prevents photo-degradation of QDs during long-term light irradiation.

Journal: :Nanoscale 2014
Hiroshi Sugimoto Minoru Fujii Yuki Fukuda Kenji Imakita Kensuke Akamatsu

We report a novel method to prepare silicon quantum dots (Si-QDs) having excellent stability in water without organic-ligands by simultaneously doping phosphorus and boron. The codoped Si-QDs in water exhibit bright size-tunable luminescence in a biological window. The luminescence of codoped Si-QDs is very stable under continuous photoexcitation in water.

2014
P Kumar Y Ma S Kumar E Clarke B D Gerardot J C Rodriguez Luna J M Cooper

Quantum dots (QDs) embedded in photonic nanowires have proved promising as sources of single photons [1–3] for applications in quantum information protocols. Investigations have shown that the brightness of these light sources depend on the diameter and taper of the nanowire as well as the axial and lateral position of the quantum dot dipole within it. In addition to efficient collection of the...

Journal: :Chemical communications 2014
Rijun Gui Hui Jin Xifeng Liu Zonghua Wang Feifei Zhang Jianfei Xia Min Yang Sai Bi

Under the two-photon excitation, upconversion luminescent "INHIBIT" and "OR" logic gates of water-dispersed CdTe quantum dots (QDs) were constituted by conjugating the QDs with dopamine. This facilitated the development of a novel QDs-based upconversion luminescent probe for efficient turn-on sensing of glutathione.

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