摘要:

Cantilever based, fully metal coated near‐field optical probes have been studied theoretically and experimentally. It is shown that these probe structures allow light transmission, even if the tip is entirely covered with a 60nm thick metallic film. The calculated far‐field intensity patterns correspond to those of the experimental measurements. Furthermore, when the injected light is radially polarized, the calculations predict a high electromagnetic field confinement in the near‐field. As expected from these simulations, strong light confinement and hence, high optical resolution is obtained when discriminating the linear polarization component of the field. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639801

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Spectrally resolved light intensity images of self‐assembled InAs/Al0.6Ga0.4As quantum dots (QDs) were measured by injecting electrons from the tip of a scanning tunneling microscope at room temperature. Localized bright features were observed in the images for different photon energies. The light emission spectra measured over the bright features showed a single emission peak having different peak energies with linewidths of 30–45 meV. By comparing these results with atomic‐force‐microscope images and photoluminescence spectra, we identified the observed bright features with the ground‐state interband transition of individual InAs QDs. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639802

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We analyze the electroluminescence spectrum of an STM‐tip‐induced quantum dot in a GaAs surface layer. A flexible model has been developed, that combines analytical and numerical methods and describes the key features of many‐particle states in the STM‐tip induced quantum dot. The dot is characterized by its depth and lateral width, which are experimentally controlled by the bias and the tunneling current. We find, in agreement with experiment, that increasing voltage on the STM‐tip results in a red shift of the electroluminescence peaks, while the peak positions as a function of the electron tunneling current through the STM‐tip reveal a blue shift. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639803

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The emission spectra of STM‐induced luminescence for Au(111) with Pt‐Ir alloy have been studied. We have observed the STM‐tip dependent emission spectra. The emission spectra with Pt‐Ir(20&percent;) tip are not well reproduced, showing various spectra depending on the nature of the tip apex, while the spectra with pure Pt or Pt‐Ir(10&percent;) tips are reproducibly obtained. The STM‐induced emission spectra for different STM tips have been calculated by the electromagnetic theory with complex dielectric functions defined in two different ways for alloy material, and compared with the experimental results. The characteristics of the spectra are interpreted in terms of the one mode type and two mode type depending on the composition rates. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639804

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We report on an efficient self‐consistent technique for quantum transport of nanostructures bridged between two metallic electrodes. The method is based on the density‐functional theory using the recursion‐transfer‐matrix (RTM) method with a separable form of norm‐conserving nonlocal pseudopotentials. With this method, we have performed calculations of the conductance through Al atomic‐wires with various kinds of a single atom mixed at the contact to one electrode. We found that the bonding nature of the atom at the contact affects the transport properties significantly. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639805

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present first‐principles calculations of electron emission from an Al atom adsorbed on metallic jellium electrode using the first‐principles recursion‐transfer‐matrix (RTM) method with the nonlocal pseudopotential. The original boundary condition of RTM method is modified to express a constant electric field far into the vacuum region. We describe the details of the condition, and show the microscopic distributions of the electron emission current and the potential barrier for the system. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639806

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A theoretical analysis of scanning capacitance microscopy is presented. By solving and matching the corresponding Laplace and Poisson equations for vacuum and semiconductor, the potential and charge distributions induced by a rounded tip in a semiconductor sample were found and used to calculate the capacity and its voltage derivative. The results allow us to analyze the dependence of the capacitance on the semiconductor doping level, applied voltage, and tip geometry, and to estimate the spatial resolution of such measurements. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639807

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In a search to control charge injection and detection with an atomic force microscope, dynamic force curves are investigated in the presence of an electrostatic tip‐sample coupling. An analytical study, using a plane capacitor model, provides results in good agreement with experimental data, in particular for the hysteretic behavior of the tip. Moreover, the plane capacitor model furnishes an estimation of the detected charge in our experiment of 360 electrons on aSiO2surface. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639808

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Polarization energiesW(z) induced by charged particles moving perpendicular to the vacuum‐semiconductor interfaces have been calculated on the basis of the perturbation theory. The adopted approach takes into account both spatial and temporal dispersions of the electrode dielectric functions &Vegr;(k, &ohgr;). It is shown that the quantum‐mechanical character of thek‐dependence of &Vegr;(k, &ohgr;) leads to the smootherW(z) dependence than in the semiclassical case and to the drastic reduction of the dynamical corrections to the static image forces. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639809

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The limitations of traditional probe microscopy and possibilities to overcome them are considered. Using of the resonance‐tunneling effect is proposed and this effect is shown to make it possible to obtain information not only about the first atomic layer of the surface but also about the second, third atomic layer and some subsequent ones. Calculations are made of effectiveness of using the resonance tunneling for studying deep‐laid atomic layers of the surface. The expression of the tunneling current in case of the resonance tunneling has been proposed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639810

出版商:AIP    

年代:1903

数据来源: AIP