Colloidal Nanocrystals (colloidal + nanocrystal)

Distribution by Scientific Domains

Selected Abstracts

Interface Modifications of InAs Quantum-Dots Solids and their Effects on FET Performance

Michal Soreni-Harari
Abstract InAs nanocrystals field-effect transistors with an ON/OFF ratio of 105 are reported. By tailoring the interface regions in the active layer step-by-step, the evolution of the ON/OFF ratio can be followed from approximately 5 all the way to around 105. The formation of a semiconducting solid from colloidal nanocrystals is achieved through targeted design of the nanocrystal,nanocrystal interaction. The manipulation characteristics of the nanocrystal interfaces include the matrix surrounding the inorganic core, the interparticle distance, and the order of nanocrystals in the 3D array. Through careful analysis of device characteristics following each treatment, the effect of each on the physical properties of the films are able to be verified. The enhanced performance is related to interparticle spacing, reduction in sub-gap states, and better electronic order (lower , parameter). Films with enhanced charge transport qualities retain their quantum-confined characteristics throughout the procedure, thus making them useful for optoelectronic applications. [source]

End-to-End Assembly of Shape-Controlled Nanocrystals via a Nanowelding Approach Mediated by Gold Domains,

Albert Figuerola
Welding nanocrystals for assembly: The welding of Au domains grown on the tips of shape-controlled cadmium chalcogenide colloidal nanocrystals is used as a strategy for their assembly. Iodine-induced coagulation of selectively grown Au domains leads to assemblies such as flowerlike structures based on bullet-shaped nanocrystals, linear and cross-linked chains of nanorods, and globular networks with tetrapods as building blocks. [source]

Anisotropic Shape Control of Colloidal Inorganic Nanocrystals,

S.-M. Lee
Abstract The systematic shape control of colloidal nanocrystals including one-dimensional (1D) nanorods remains a key issue in the "bottom,up" approach of nanoscience. Here, we examine the anisotropic structural evolution of various semiconductor nanocrystals and systematically elucidate the key growth parameters for their shape control. The crystalline phase of nucleating seeds and kinetic growth regimes controlled by changing growth parameters are crucial for the determination of the 1D nanocrystal geometry. [source]

MBE overgrowth of ex-situ prepared CdSe colloidal nanocrystals

M. Rashad
Abstract We present a growth technique, which combines molecular beam epitaxy of ZnSe and externally wet-chemically prepared, colloidal NCs of CdSe to achieve fully integrated monolithic epitaxial heterostructures. Our results show that wet-chemically prepared semiconductor nanocrystals can be incorporated in an epitaxally grown crystalline cap layer. We investigated CdSe core, CdSe/ZnSe and CdSe/ZnS core/shell nanocrystals (NCs) overgrown with cap layers of ZnSe, where the thickness was varied between 20-40 nm. In this paper we discuss PL measurements of overgrown NCs as a function of the cap layer thickness and compare the results with the PL of NCs in solution. A distinct blue shift of the PL is observed when the core/shell dots are overgrown by ZnSe. We present a model which explains this blue shift as resulting from dissolution of the shell of the dots during the overgrowth ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Non-Blinking Semiconductor Colloidal Quantum Dots for Biology, Optoelectronics and Quantum Optics

CHEMPHYSCHEM, Issue 6 2009
Piernicola Spinicelli
Abstract Twinkle, twinkle: The blinking of semiconductor colloidal nanocrystals is the main inconvenience of these bright nanoemitters. There are various approaches for obtaining non-blinking nanocrystals, one of which is to grow a thick coat of CdS on the CdSe core (see picture). Applications of this method in the fields of optoelectronic devices, biologic labelling and quantum information processing are discussed. The blinking of semiconductor colloidal nanocrystals is the main inconvenience of these bright nanoemitters. For some years, research on this phenomenon has demonstrated the possibility to progress beyond this problem by suppressing this fluorescence intermittency in various ways. After a brief overview on the microscopic mechanism of blinking, we review the various approaches used to obtain non-blinking nanocrystals and discuss the commitment of this crucial improvement to applications in the fields of optoelectronic devices, biologic labelling and quantum information processing. [source]