نتایج جستجو برای: nanocrystal

تعداد نتایج: 3002  

2013
Yu-Hsien Lin Chao-Hsin Chien

This study proposes a novel HfO2 nanocrystal memory on epi-SiGe (Ge: 15%) channel. Because SiGe has a smaller bandgap than that of silicon, it increases electron/hole injection and the enhances program/erase speeds. This study compares the characteristics of HfO2 nanocrystal memories with different oxynitride tunnel oxide thicknesses on Si and epi-SiGe substrate. Results show that the proposed ...

Journal: :Optics express 2008
Evren Mutlugun Ibrahim Murat Soganci Hilmi Volkan Demir

We propose and demonstrate semiconductor nanocrystal based photovoltaic scintillators integrated on solar cells to enhance photovoltaic device parameters including spectral responsivity, open circuit voltage, short circuit current, fill factor, and solar conversion efficiency in the ultraviolet. Hybridizing (CdSe)ZnS core-shell quantum dots of 2.4 nm in diameter on multi-crystalline Si solar ce...

Journal: :Nano letters 2005
Julie S Biteen Domenico Pacifici Nathan S Lewis Harry A Atwater

We report local-field-enhanced light emission from silicon nanocrystals close to a film of nanoporous gold. We resolve photoluminescence as the gold-Si nanocrystal separation distance is varied between 0 and 20 nm and observe a fourfold luminescence intensity enhancement concomitant with increases in the coupled silicon nanocrystal/nanoporous gold absorbance cross section and radiative decay ra...

Journal: :Optics express 2008
Sedat Nizamoglu Hilmi Volkan Demir

We propose and demonstrate hybrid white light emitting diodes enhanced with resonant nonradiative energy transfer in CdSe/ZnS core/shell nanocrystal solids integrated on near-UV InGaN/GaN LEDs. We observe a relative quantum efficiency enhancement of 13.2 percent for the acceptor nanocrystals in the energy gradient mixed assembly, compared to the monodisperse phase. This enhancement is attribute...

1999
S. H. Choi K. L. Wang M. S. Leung G. W. Stupian N. Presser S. W. Chung G. Markovich S. H. Kim J. R. Heath

In this article, we present a new method for fabricating precisely defined nanometer scale photoresist wire patterns. The Langmuir technique was utilized to form high aspect ratio lamellae, or wire patterns, of Ag nanocrystals at the air/water interface, and these patterns were transferred onto resist-coated substrates as a Langmuir–Schaeffer film and as a shadowmask. The wire patterns were tra...

2015
Sara Bogren Andrea Fornara Frank Ludwig Maria del Puerto Morales Uwe Steinhoff Mikkel Fougt Hansen Olga Kazakova Christer Johansson O. Thompson Mefford

This study presents classification of different magnetic single- and multi-core particle systems using their measured dynamic magnetic properties together with their nanocrystal and particle sizes. The dynamic magnetic properties are measured with AC (dynamical) susceptometry and magnetorelaxometry and the size parameters are determined from electron microscopy and dynamic light scattering. Usi...

Journal: :Mathematical and Computer Modelling 2013
Weiguo Hu Mohd Fairuz Budiman Makoto Igarashi Ming-Yi Lee Yiming Li Seiji Samukawa

Within the envelop-function framework, we developed the finite element method to calculate theminibands in the realist Silicon nanocrystal array. This method clearly reveals the miniband formation and accurately calculates the E–K dispersion relationship. In the simple 1D array, the deduced miniband structure matches well with the analytic Kronig–Penney method. More importantly, it can better s...

Journal: :Physical review letters 2004
Dmitriy V Melnikov James R Chelikowsky

Electronic properties of phosphorus donors in hydrogenated silicon nanocrystals are investigated using a real-space ab initio pseudopotential method for systems with up to 500 atoms. We present calculations for the ionization energy, binding energy, and electron density associated with the doped nanocrystal. We find that the ionization energy for the nanocrystal is virtually independent of size...

1999
Todd D. Krauss Louis E. Brus

The electrostatic properties of individual CdSe nanocrystals are directly measured using electrostatic force microscopy (EFM) in dry air at room temperature. We determine that the static dielectric constant of CdSe nanocrystals with diameters 5 nm is uniform. However, the charge per nanocrystal is nonuniform, with some nanocrystals possessing a positive charge. Furthermore, a small fraction of ...

Journal: :The journal of physical chemistry. B 2005
Robert M Kraus Pavlos G Lagoudakis Josef Müller Andrey L Rogach John M Lupton Jochen Feldmann Dimitri V Talapin Horst Weller

We study the interplay between Auger effects and ionization processes in the limit of strong electronic confinement in core/shell CdSe/ZnS semiconductor nanocrystal quantum dots. Spectrally resolved fluorescence decay measurements reveal a monotonic increase of the photoluminescence decay rate on excitation density. Our results suggest that Auger recombination accelerates ionization processes t...

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