Fabrication of electrochemical nanoelectrode for sensor application Rusing focused ion beam technology

The capabilities and applications of the focused ion beam (FIB) technology for detection of an electrochemical signal in nanoscale area are shown. The FIB system, enabling continuous micro- and nanofabrication within only one equipment unit, was used to produce a prototype of electrochemical nanometer-sized electrode for sensor application. Voltammetric study of electrochemically active compound (ferrocenemethanol) revealed the diffusion limiting current (12 pA), corresponding to a disc (planar) nanoelectrode with about 70 nm diameter of contact area. This size is in a good accordance with the designed contact-area (50 nm × 100 nm for width × thickness) of the FIB-produced nanoelectrode. It confi rms that produced nanoelectrode is working properly in liquid solution and may enable correct measurements in nanometer-sized regions

Visible Light Emission from Porous Silicon

The aim of this paper is the study of porous Si prepared by preferential anodic dissolution in concentrated HF acid solutions. Porous silicon layers exhibited extremely efficient luminescence in the 700-900 nm range at room temperature. Basic characteristics of this luminescence strongly suggest the intrinsic origin of the process, directly related to quantum confinement. The additional transmission-electron-microscopy and electron-diffraction studies - were performed to support hypothesis that luminescence originates from silicon nanostructures

Effect of Secondary Electroluminescence on Cathodoluminescence and Other Luminescence Measurements

Cathodoluminescence and photoluminescence measurements are commonly accepted as revealing local properties of a specimen region excited by a beam of electrons or photons. However, in the presence of a strong electric field (e.g. a junction) an electron (or light/laser) beam-induced current is generated, which spreads over the structure. A secondary non-local electroluminescence, generated by this current and detected together with the expected luminescence signal, may strongly distort measurement results. This was confirmed by cathodoluminescence measurements on test structures prepared by focused ion beam on AlGaAs/GaAs/InGaAs laser heterostructures. Methods for minimizing the distortion of measured luminescence signals are presented

Dependence of Nanoelectronic-Structure Defect Detection by Cathodoluminescence on Electron Beam Current

The dependence of defect detection by cathodoluminescence in a scanning electron microscope on the electron beam current is considered. The examined specimens are AlGaAs/GaAs laser heterostructures with InGaAs quantum well. It is shown that for low electron beam currents, which are typically used, the uniform cathodoluminescence is observed, while for the increasing high electron beam current the oval defects become more and more visible. The influence of electrical properties of the structure on the luminescence detection is explained

Resonant Cavity Enhanced Photonic Devices

In the present paper we review our recent works on technology, basic physics, and applications of one-dimensional photonic structures. We demonstrate spontaneous emission control in In$\text{}_{x}$Ga$\text{}_{1-x}$As/GaAs planar microcavities with distributed Bragg reflectors. In general, observed trends are in agreement with theoretical predictions. We also demonstrate the operation of resonant-cavity light emitting diodes and optically pumped vertical cavity light emitting diodes developed recently at the Department of Physics and Technology of Low-Dimensional Structures of the Institute of Electron Technology

Characterization of SOI fabrication process using gated-diode measurements and TEM studies

SOI fabrication process was characterized using electrical and TEM methods. The investigated SOI structures included partially and fully depleted capacitors, gated diodes and transistors fabricated on SIMOX substrates. From C-V and I-V measurements of gated diodes, the following parameters of partially depleted structures were determined: doping concentration in both n- and p-type regions, average carrier generation lifetimes in the region under the gate and generation velocity at top and bottom surfaces of the active layer. Structures with short lifetime were studied using a transmission electron microscope. TEM studies indicate that the quality of the active layer in the investigated structures is good. Moreover, these studies were used to verify the thicknesses determined by means of electrical characterization methods

Oxygen Precipitation in Si:O Annealed under High Hydrostatic Pressure

Effect of hydrostatic pressure up to 1.2 GPa on oxygen-implanted silicon, Si:O (O$\text{}^{+}$ dose, D, within the 6×10$\text{}^{17}$-2×10$\text{}^{18}$ cm$\text{}^{-2}$ range), treated at 1230-1570 K, was investigated by X-ray, transmission electron microscopy and photoluminescence methods. The pressure treatment affects oxygen precipitation and defect creation, especially in low oxygen dose implanted Si:O (D=6×10$\text{}^{17}$ cm$\text{}^{-2}$). Such investigation helps in understanding the stress related phenomena in Si wafers with buried insulating layer

Transmission electron microscopy of In(Ga)As quantum dot structure

The application of transmission electron microscopy (TEM) to the investigation of In(Ga)As quantum dot (QD) structures grown on GaAs substrates is reviewed. Using various examples of the QD structures the advantages of using TEM for the analysis of QDs are presented. From plan-view TEM images the areal density of dots can be determined in real structures where QDs are embedded in the structure. Cross-sectional TEM images inform us about the real geometry of the structure, the shape, width and height as well as the distribution of QDs. It is especially useful for the investigations of multilayer QD structures