摘要:

Scanning tunneling microscope is used to create local surface modifications by means of ion impact damage. Graphite has been used as a test case to demonstrate this local surface sputtering. Using a 0.1‐μs voltage pulse of −30 to −140 V applied to the sample in a rough vacuum of 10−2Torr, a confined area of damage (typically about 100 Å in diameter) is usually obtained. The damaged area consists of several layers of terraces. Defects of the size of a few atoms can also be found. Electronic perturbations caused by defects can form superlattices with a spacing three times that of the graphite lattice. From measurements of the threshold voltage for the discharge, the minimum radius of curvature of the tip can be estimated. The potential applications of this technique and comparison with previous results are discussed.

ISSN:0734-211X    

DOI:10.1116/1.585200

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

We have developed an ultrahigh vacuum (UHV) scanning tunneling microscope (STM) designed to work in conjunction with a commercial, high‐vacuum scanning electron microscope (SEM). The STM resides in its own UHV subchamber which is housed in the JEOL 820 SEM. We have used the SEM to image the STM tip and its location on the sample. This instrument was built to fabricate and study metallic and contamination resist nanostructures and devices on semiconductor surfaces. To create these structures, we use a technique developed in our lab which uses the STM to dissociate organometallic gases or organic residues on semiconductor surfaces. Our system allows precise alignment of the STM‐fabricated structures with underlying macroscopic contact pads. The UHV subchamber, which includes standard UHV sample preparation and analysis equipment, is required to prepare atomically flat and clean samples.

ISSN:0734-211X    

DOI:10.1116/1.585201

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Recent results employing scanning tunneling microscope‐based techniques for the generation of nanometer‐scale patterns on passivated semiconductor surfaces are presented. Preparation and characterization of hydrogen‐passivated silicon and sulfur‐passivated gallium arsenide surfaces are described and the determination of the chemical and morphological properties of the patterned regions by scanning electron microscopy and time‐of‐flight secondary ion mass spectrometry are discussed. Our recent demonstration that ultrashallow, oxide features written by scanning tunneling microscope (STM) can serve as an effective mask for selective‐area GaAs heteroepitaxy on silicon is used to illustrate key requirements necessary for the realization of a unique, STM‐based nanotechnology.

ISSN:0734-211X    

DOI:10.1116/1.585202

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The use of a scanning tunneling microscope (STM) has become a powerful technique for getting information on the topography of a conducting or semiconducting surface as well as for performing local tunneling spectroscopy. But there is also an increasing interest to use this particular technique for the fabrication of nanostructures in a desired and well‐controlled way. Such structures are valuable for the investigation of the physics in small dimensions as well as for the development of new devices that take advantage of quantum size effects. The analysis of the processes creating nanostructures can provide important information about different interactions between the tip, the sample and their surrounding. In this letter we present one of the mechanisms involved in the fabrication of such nanostructures on glassy metals. We investigated the response of different glassy metals to our fabrication process and compared it to the theoretical predictions derived from the solution of the thermal diffusion equation. Furthermore, we will show a method to analyze the fabrication process by measuring the current during the creation of the structures.

ISSN:0734-211X    

DOI:10.1116/1.585203

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A class of devices based on the atomic force microscope [Phys. Rev. Lett.56, 930 (1986)] is proposed that would enable imaging with tips of atomically defined structure. These molecular tip array (MTA) systems would enable sequential application of tips with differing structures to a single sample, limited to a small substrate area. MTAs with suitable binding sites can enable nanofabrication via positional chemical synthesis exploiting local effective concentration enhancements of ∼108. A method for canceling or inverting the net van der Waals attraction between a tip and a substrate in a fluid medium is suggested, and a new analysis of imaging forces for proteins is presented.

ISSN:0734-211X    

DOI:10.1116/1.585204

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

We have demonstrated that a gold scanning tunneling microscope (STM) tip can be used as a miniature solid‐state emission source for directly depositing nanometer‐size gold structures. The process has been demonstrated in ultrahigh vacuum on gold substrates, and in air on gold and platinum substrates. Studies made in air suggest that the process is fast, repeatable, and field‐induced. The emission mechanism is believed to be field evaporation of tip atoms, which is enhanced by the close proximity of the substrate. The technique has been used to write several thousand features with no apparent degradation of the tip’s ability to write. Elevated and room temperature studies show the written structures to be stable over periods of weeks, in contrast to some previous STM measurements of gold self‐diffusion.

ISSN:0734-211X    

DOI:10.1116/1.585205

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Chemically assisted ion beam etching (CAIBE) and reactive ion etching (RIE) are two popular dry etching techniques routinely used in the fabrication of submicron features. We have used bothinsituandexsituRaman spectroscopy to study the effects of dry etching on the depletion layer in heavily doped GaAs. We find that both CAIBE and RIE produce large numbers of traps that produce an insulating layer on the surface. CAIBE using ion energies greater than 2 keV also produces a damaged layer. For both techniques the use of chlorine based species reduces both traps and damage. Sputtering with chlorine alone, is shown to be able to eliminate both damage and traps. Finally, Raman spectroscopy is shown as a powerfulinsitutool for studying etch damage.

ISSN:0734-211X    

DOI:10.1116/1.585594

出版商:American Vacuum Society    

年代:1991

数据来源: AIP