Search results for "Semiconductor"
showing 10 items of 974 documents
Pathologies currently identified by exhaled biomarkers.
2013
Ancient Greek physicians already knew that the smell of human breath could provide a clue to the pathology. Nowadays, volatile breath biomarkers are known to be released in a broad range of diseases. However, their identification, isolation, and quantification as indicative of relevant alterations in clinical status have required the development of new techniques and analytical methods. Breath sample analysis encounters several obstacles. Particularly, there is a need of a system that could work in a continuous manner, with the low concentration and small volume of a sample. Herein we review, in the light of literature and our experience, clinical applications of the metal oxide semiconduct…
Room-temperature polariton luminescence from a bulk GaN microcavity
2006
We report strong exciton-photon coupling at room temperature in a hybrid high quality bulk 3 lambda/2 GaN cavity with a bottom lattice-matched AlInN/AlGaN distributed Bragg reflector through angle-resolved polarized photoluminescence (PL). Coupling of the optically active free excitons (X-A, X-B, and X-C) to the cavity mode is demonstrated, with their contribution to the PL spectra varying with polarization. Under TE polarization, exciton oscillator strengths for X-A and X-B are about one order of magnitude larger than in bulk GaAs. Photoluminescence exhibits a strong bottleneck effect despite its thermal lineshape.
Competition between memory-keeping and memory-erasing decoherence channels
2014
We study the competing effects of simultaneous Markovian and non-Markovian decoherence mechanisms acting on a single spin. We show the existence of a threshold in the relative strength of such mechanisms above which the spin dynamics becomes fully Markovian, as revealed by the use of several non-Markovianity measures. We identify a measure-dependent nested structure of such thresholds, hinting at a causality relationship among the various non-Markovianity witnesses used in our analysis. Our considerations are then used to argue the unavoidably non-Markovian evolution of a single-electron quantum dot exposed to both intrinsic and Markovian technical noise, the latter of arbitrary strength.
The use of quantum dots in organic chemistry
2009
Abstract We discuss the main mechanisms of interaction between quantum dots (QDs) of different types and organic molecules within the framework of the use of photo-physical properties of colloidal semiconductor nanoparticles for sensing organic and biochemical compounds. We reviewed the recent literature in the field to provide a picture of the state of the art of our knowledge and perspectives on this challenging field. Bearing in mind analysis in organic chemistry based on luminescence and electrochemical changes, we discuss surface interaction based on the use of QDs capped with thiol, cystein, citrate, surfactant, purine and nitroxides, and we explain ligand-analyte, bioconjugate-analyt…
1.3 µm GaInNAs optically-pumped vertical cavity semiconductor optical amplifier
2003
A GaInNAs/GaAs vertical cavity semiconductor optical amplifier (VCSOA) is reported. This is believed to be the first monolithic VCSOA operating at 1.3 mum. Under continuous-wave optical pumping in a singlemode fibre coupled format, gain figures of up to 17.7 dB were achieved. Amplification with 12 GHz bandwidth,was obtained at 12.8 dB peak gain.
Ultrafast Carrier Redistribution in Single InAs Quantum Dots Mediated by Wetting-Layer Dynamics
2019
Optical studies of single self-assembled semiconductor quantum dots (QDs) have been a topic of intensive investigation over the past two decades. Due to their solid-state nature, their electronic and optical emission properties are affected by the particular crystal structure as well as many-body-carrier interactions and dynamics. In this work, we use a master equation for microstates (MEM) model to study the carrier capture and escape from single QDs under optical nonresonant excitation and under the influence of a two-dimensional (2D) carrier reservoir (the wetting layer). This model reproduces carrier dynamics from power-dependent and time-resolved microphotoluminescence experiments . Du…
Acousto-electric single-photon detector
2007
We propose a novel concept for a semiconductor-based single-photon detector for quantum information processing, which is capable of discriminating the number of photons in a light pulse. The detector exploits the charge transport by a surface acoustic wave (SAW) in order to combine a large photon absorption area (thus providing high photon collection efficiency) with a microscopic charge detection area, where the photo generated charge is detected with resolution at the single electron level using single electron transistors (SETs). We present preliminary results on acoustic transport measured in a prototype for the detector as well as on the fabrication of radio-frequency single-electron t…
Pressure-induced phase transition and bandgap collapse in the wide-bandgap semiconductor InTaO4
2016
A pressure-induced phase transition, associated with an increase of the coordination number of In and Ta, is detected beyond 13 GPa in InTaO4 by combining synchrotron x-ray diffraction and Raman measurements in a diamond-anvil cell with ab initio calculations. High-pressure optical-absorption measurements were also carried out. The high-pressure phase has a monoclinic structure that shares the same space group with the low-pressure phase (P2/c). The structure of the high-pressure phase can be considered as a slight distortion of an orthorhombic structure described by space group Pcna. The phase transition occurs together with a unit-cell volume collapse and an electronic band-gap collapse o…
Selective modification of the band gaps of GaInNas/GaAs structures by quantum well intermixing techniques
2003
We report the unambiguous demonstration of controlled quantum well intermixing (QWI) in the technologically important GaInNAs/ GaAs 1.3 mum material system. QWI is a key technique to selectively modify the band gap of quantum wells, which has found broad application in semiconductor lasers and photonic integrated circuits (PICs). Extending such technology to GaInNAs/GaAs structures is highly desirable due to the technologically advantageous properties of this material system. Here, we investigate well-characterized GaInNAs quantum well material which has been annealed "to saturation" before QWI processing to allow unambiguous interpretation of results. After RTA at 700 degreesC for similar …
Assemblies of semiconductor quantum dots and light-harvesting-complex II
2010
Abstract A novel hybrid system composed of fluorescent core/shell semiconductor quantum dots and the light harvesting complex II (LHCIIb), a membrane protein of higher plants, has been assembled. Experiments with different mutants show that hybrid formation can be mediated by a C-terminal His 6 tag attached to the protein as well as by positive charges of the first N-terminal amino acids of LHCIIb. Quenching of the quantum dot fluorescence upon binding of LHCIIb was partially attributed to energy transfer from the quantum dots to LHCIIb.