摘要:

We have investigated a fabrication technique of nm size Si wires utilizing a bevelSiO2wall on a (111) surface as an electron cyclotron resonance (ECR) plasma etching mask. The bevel (111) surface is obtained by anisotropic etching of a (100) silicon-on-insulator layer. Small-size Si wires of around 20–25 nm are successfully obtained underneath the bevelSiO2wall. It is shown that a local oxidation of silicon process to form the bevelSiO2wall affects the cross-sectional shape of the small-size Si wires in the ECR plasma etching process. It is also indicated that a self-limiting oxidation takes place in such small-size Si wires. By thermal oxidation of the small-size Si wires, an ultrasmall cross-sectional size of around 1×nm2is realized. In addition, a Coulomb blockade effect is observed in an experimental nm size Si wire metal-oxide-semiconductor field-effect transistor.

ISSN:1071-1023    

DOI:10.1116/1.589289

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Connections between two macroscopic metallic (gold, copper, silver, platinum, and tungsten) wires have been investigated by transmission and scanning electron microscopy. The results show that metallic contacts exist but do not break cleanly. They are stretched into many filaments or threads of nanometer size leading to nanowire formation as time passes.

ISSN:1071-1023    

DOI:10.1116/1.589290

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Silicon nanowires (whiskers) have been grown on Si(111) via the vapor–liquid–solid (VLS) reaction using silane as the Si source gas and Au as the mediating solvent. The silane partial pressure and temperature ranges were 0.01–1 Torr and 320–600 °C, respectively. Growth at high partial pressure and low temperature leads to the growth of Si nanowires as thin as 10 nm. These wires are single crystals but exhibit growth defects such as bending and kinking. Lowering the silane partial pressure leads to an increase in the wire width and a reduction in the tendency to form growth defects. At low pressure, 40–100 nm wide well-formed wires have been grown at 520 °C. The VLS reaction using silane allows the growth of Si wires, which are significantly thinner than those grown previously usingSiCl4.

ISSN:1071-1023    

DOI:10.1116/1.589291

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Soft-vacuum plasma processes have been increasing in importance for high-quality, large-area, and high-rate fabrication of thin films for practical applications. In such processes, the characteristics of the deposited species (considered to be clusters) have been of interest. However, even their size has not been sufficiently investigated because of the many difficulties arising due to the high pressure conditions and the steep temperature and concentration gradients in the boundary layer, especially when the species change easily during measurements. In this work, we describe a new method of using a microtrench, to determine the mean cluster sizedc,diffusivityD, and sticking probabilityηwithout any disturbances to the plasma or the boundary layer conditions. Using this method, the cluster size in the deposition of YBa2Cu3O7−xhigh-Tcsuperconductor by plasma flash evaporation is successfully measured as 1–9 nm, with the parameters of source powder feeding rate from 60 to 350 mg/min, torch substrate distance from 270 to 360 mm in 200 Torr, 50 kW 95%O2-5%Ar inductively coupled rf plasma.

ISSN:1071-1023    

DOI:10.1116/1.589292

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

In order to obtain atomic resolution in a transmission electron microscope, a piezo-driven nanostage with subnanometer stability is under development. Inertial sliding motion is used to move the nanostage table in the plane perpendicular to gravity. One of the most important parameters on the way to such a nanostage is the design of the nanostage table supports. Through several experiments, the stability of two different nanostage table supports is studied: a kinematic and a nonkinematic support. In order to explain the submicrometer and nanometer stage table drift measured in the direction parallel to gravity, a subnanometer contact theory is presented. This theory explains the stage table drift by the following parameters: the size of the apparent contact area of the support, the gravity forces working on the support, the multimolecular layer of adsorbed water molecules on all contact surfaces, creep in the contact points and settling of the contact through microsliding at the contact points. For the initial placement of a nonkinematic support in ambient air with an apparent contact area size of 15×15mm2,a stage table drift of 100 nm over 30 min was measured, which almost exactly followed a logarithmic curve. This drift reduced to about 45 nm when the support was placed in a low vacuum, where the number of layers of adsorbed water molecules on the support surfaces is reduced to one or two. Filling the vacuum chamber with nitrogen gas resulted in an even lower stage table drift (25 nm). Stage table drift after single inertial sliding steps is about 25% of the initial amount of drift. In case of a kinematic support, the apparent contact area reduces significantly and stage table drifts after initial placement of 1 up to 3 nm were found. The drift after single inertial sliding steps is on the same order of magnitude. These drifts are attributed to contact creep, which was minimized by optimization of the material selection of both contact surfaces. A combination of two hard surfaces showed almost no creep at the subnanometer level. Therefore, this highly stable kinematic support suits the nanostage application very well.

ISSN:1071-1023    

DOI:10.1116/1.589293

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

This article presents a potential image processing method for determining the in-plane geometrical distortion of a scanning tunneling microscope (STM) image and calibrating it using a regular crystalline lattice, and describes the results obtained in comparative length measurements in the range of about 1 μm using a regular crystalline lattice as a reference scale and a dual tunneling unit-STM (DTU-STM) as a detector. The method is based on two-dimensional fast Fourier transform analysis. The DTU-STM with oneX-Ystage and two tunneling units independently controlled in theZ-axis direction was utilized for comparative length measurement. To improve the measurement accuracy, the present method is used to process the raw images obtained from the DTU-STM. The results of experiments, in which the cleaved surface of highly oriented pyrolytic graphite is used as a reference scale for measurement of lengths on the order of 1 μm, demonstrate the feasibility of the present image processing method and the possibility of comparative length measurement with subnanometer resolution using the DTU-STM.

ISSN:1071-1023    

DOI:10.1116/1.589294

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

This article reports on the first “standalone” optical atomic force microscope (AFM) based on an integrated Fabry–Pérot AFM sensor. The new AFM consists of two components: a cantilever with an integrated tip and a Fabry–Pérot cavity and an optical system for supply and detection of the light. A batch process for the reproducible production of the new Fabry–Pérot cantilever by thin film technology is described. The tip diameters achievable are below 10 nm. The Fabry–Pérot gap of approximately 7μm realized reduces thermal drift and phase noise. The optical system is produced by high precision mechanics. It consists of one part that is fixed to the piezo tube and another part that can be exchanged. The advantage of the new AFM is the high resolution of the integrated optical detection system combined with an easy handling system for cantilever exchange without any adjustment. This makes the approach very attractive as a standard tool for inspection in semiconductor industry, surface manipulation on a nanometer scale, or surface studies in ultrahigh vacuum.

ISSN:1071-1023    

DOI:10.1116/1.589295

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Individual chains of the rigid-rod polymer phthalocyaninepolysiloxane (PcPS) have been deposited and immobilized on top of nanofabricated metal electrodes. This is realized by embedding sparsely distributed PcPS polymers in a monolayer of cellulose using the Langmuir–Blodgett deposition technique. Atomic force microscopy was used to study the resulting spatial arrangement of these one-dimensional conducting polymers. Images of the polymer chains were obtained with a lateral resolution of better than 1 nm. Inspection of the polymers near the edges of the electrodes demonstrates that the monolayer structure is not perturbed by the 15 nm high electrodes. With this procedure, it appears to be possible to bridge two closely spaced electrodes with individual PcPS polymer chains.

ISSN:1071-1023    

DOI:10.1116/1.589296

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

In this article the results of a numerical simulation of the thermal and mechanical properties of micromechanical sensors are described. Finite element analysis is used to model the response of the composite cantilever to temperature variations. The simulations consider triangular shaped cantilevers in air and water environments and under different configurations of thermal loading. The models utilize conditions from actual experiments which are conducted in parallel. Good agreement between numerical and experimental results studied so far allows us to use our numerical simulation to confidently predict the performance of the sensor under novel operating conditions and to optimize the sensor design for specific applications.

ISSN:1071-1023    

DOI:10.1116/1.589297

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Numerical simulations of the interaction of optical fields with metal tips, such as in photofield emission and laser-assisted scanning tunneling microscopy, show that the electric field at the apex of the tip is much greater than that in the incident optical beam. Calculations were made using the method of moments with two models of the tip; a conical frustrum with hemispherical end caps, and a paraboloid. A large number of subvolumes (850–1000) was used to decrease the errors caused by finite matrix size with the method of moments, and it is shown that these errors have no significant effect on the results. The ratio of the optical electric field at the apex of the tip to that in the incident beam (field ratio) varies directly with the curvature at the apex, and is increased by raising the tip length and the optical wavelength. For the range of parameters used in the examples field ratios of 3–15 dB were found for incidence normal to the tip axis, and values as large as 32 dB were found for an angle of approximately 10° between the incident laser beam and the tip axis. Differences between the results for the two models and the dependence on the radius of curvature show that the field ratio must vary greatly from tip to tip.

ISSN:1071-1023    

DOI:10.1116/1.589298

出版商:American Vacuum Society    

年代:1997

数据来源: AIP