摘要:

We have utilized several processing techniques to locally modify the superconducting transition temperature and the normal state resistivity of aluminum thin films. The techniques of ion implantation, application of a magnetic overlayer, and reactive ion etching have been used to fabricateS‐Ninterfaces with controlled differences in transition temperatures and normal state resistances. Lithographic techniques and CF4reactive ion etching at low power and pressure reliably produce two‐dimensionalS‐Nstructures of desired dimensions in the limit where the transition temperatures and normal state electronic properties of the two regions are close to each other.

ISSN:0734-2101    

DOI:10.1116/1.579425

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Fine copper powder (FCP), sintered to the cryopanels of cryopumps, was evaluated as a cryosorbent for H2. A Gifford–McMahon refrigerator cooled the tested cryopanel of a two‐stage cryopump. The third stage of a three‐stage cryopump that was tested was cooled by Joule–Thomson expansion of He. 30 g of FCP were sintered to the second stage panel (20 K) of the two‐stage bakeable cryopump, whereas 10 g of FCP were sintered to the third stage panel (4.3 K) of the three‐stage bakeable cryopump. Hydrogen pumping speed, capacity, and base pressure measurements are given as a function of temperature. Cryopanel preparation and system bakeout procedures, reliably leading to pressures<10−9Pa, are given. Hydrogen thermal desorption peaks for the FCP sintered cryopanel are also reported.

ISSN:0734-2101    

DOI:10.1116/1.579426

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The cutting of cross‐linked glasses such as silica and Corning 7059 can be difficult. We conducted an experimental study to determine the feasibility of using a high‐speed waterjet to cut thin Corning 7059 glass. Cutting using either pure de‐ionized high pressure water at 380 MPa (55 000 psi) or de‐ionized water with entrained garnet abrasive was studied. The roughness of the cut surfaces was measured and compared. Photomicrographs were taken of glass examples cut at different traversing rates with pure water and with the abrasive entrained waterjet. Comparative studies of cutting with and without the entrained abrasive material showed that a cutting rate of 127 mm/min with abrasive could achieve a smoothness of about 9 μm rms. The abrasive waterjet can cut Corning 7059 glass into any desired shape. The process is safe, inexpensive, fast, and amenable to computer operation.

ISSN:0734-2101    

DOI:10.1116/1.579427

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.579428

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Practical secondary ion mass spectrometry depth resolution data show that decreasing beam energies lead to an enhanced resolution down to the lowest practical energy of 1 keV O+2at near normal incidence. For B and C in Si, the resolution full width at half‐maximum amounts to 3.1 and ∼1.4 nm, respectively. Using a retarded probing beam, we have shown that a useful flux of Si atoms can be sputtered with primary energies as low as 260 eV O+2or 130 eV O+; the Si sputter yield is also shown to be weakly dependent on the probe energy. Therefore it is predicted that this low energy is the optimum to use in a depth profiling experiment using oxygen. The predicted resolution for B and C amounts to 1.8 and 0.8 nm. Such an analytical performance would easily justify the resources required to produce ultralow energy beams on a routine basis.

ISSN:0734-2101    

DOI:10.1116/1.579429

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.579430

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Indium oxide normally exists in the body‐centered‐cubic structure. With thin films of the compound, deposited on a glass substrate by the electron beam vacuum evaporation technique, x‐ray diffraction results indicate a simple cubic structure for some films.

ISSN:0734-2101    

DOI:10.1116/1.579431

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

In this communication we describe a simple, inexpensive technique for the real‐time monitoring of epitaxial processes based on the reflection of a parallel‐polarized light that impinges onto the surface of the substrate close to the Brewster angle for the substrate material. In the case of heteroepitaxy, a quarter‐wavelength modulation of the intensity of the reflected light is observed, which contains information concerning the evolution of the optical properties as well as a record of the growth rate for the entire duration of film deposition. Changes in the amplitude of this signal provides information about deviations in bulk dielectric properties of the growing film caused by absorption and inhomogeneities in the refractive index of the film as well as changes in the surface roughness. Furthermore, under the conditions of pulsed chemical beam epitaxy (PCBE), the reflected intensity contains a periodic oscillation that is superimposed on the polarized reflectance spectroscopy (PRS) signal with an Å scale period and is maintained over thousands of Å of film growth. The periodicity of this fine structure matches the period of the sequence of precursor pulses of the PCBE process. Also, an amplitude modulation of the superimposed oscillation is observed which may be understood on the basis of the results of PRS studies of homoepitaxial growth. Under the conditions of homoepitaxy, the quarter‐wavelength oscillations in the PRS signal cease to exist since the epitaxial film and the substrate have the same dielectric function. However, the fine structure can still be observed and may be utilized for both analysis of the growth mechanism and in conjunction with the observation of heteroepitaxial growth for the same material, the real‐time monitoring of the growth rate.

ISSN:0734-2101    

DOI:10.1116/1.579432

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Collimated magnetron sputter deposition with concurrent grazing angle ion bombardment has been developed as a technique for enhancing the ability to deposit films into trenches and vias. The collimated sputtering technique uses a conventional magnetron cathode operating at low pressure (mTorr) and a physical collimator or directional filter mounted between the cathode/discharge plasma and the sample position. The collimator serves to limit the directionality of the transmitted, sputtered atoms to near‐normal incidence. A broad‐beam Kaufman‐type ion source is mounted on the sample side of the collimator such that the ion beam impacts the sample surface at grazing (5°–15°) incidence. This serves to resputter the depositing film selectively from the topmost regions of the sample surface, while lower areas, such as trenches and vias, are geometrically shielded.

ISSN:0734-2101    

DOI:10.1116/1.579433

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

ISSN:0734-2101    

DOI:10.1116/1.579434

出版商:American Vacuum Society    

年代:1995

数据来源: AIP