Superconducting Properties of v/cr Artificial Metallic Superlattices

1986 ◽  
Vol 77 ◽  
Author(s):  
B. M. Davis ◽  
J. Q. Zheng ◽  
M. R. Ma ◽  
B. Y. Jin ◽  
J. E. Hilliard ◽  
...  
Keyword(s):  
Proximity Effect ◽  
High Vacuum ◽  
Upper Critical Field ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Zero Field ◽  
Dimensional Crossover ◽  
Superconducting Properties ◽  
Sapphire Substrates ◽  
Field Transition

ABSTRACTWe have studied the superconducting properties of V/Cr superlattices. Superlattices of V100Crx, V150Crx, and V200Crx, with x varying between 3 and 80 atomic planes have been prepared. The films have a strong (110) texture and were grown on sapphire substrates at 250°C in an ultra-high vacuum system. The zero field transition temperature of the V150Crx and V200Crx, but not the V100Crx films have been adequately modeled using Werthamer's theory for proximity effect coupled films. The films have a dimensional crossover in the parallel upper critical field when the thickness of the Cr layers is about 60 atomic planes.

Hetero-Epitaxy of Group Va Metals on Sapphire

1972 ◽  
Vol 30 ◽  
pp. 492-493
Author(s):  
J. E. O'Neal ◽  
J. J. Bellina ◽  
B. B. Rath
Keyword(s):  
Thermal Contact ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Backing Plate ◽  
Sapphire Substrates ◽  
Deposition Parameters ◽  
Polishing Damage ◽  
Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

The design and study of a compact bakeable ultra-high vacuum system for calibrating absolutely low pressure gauges

Vacuum ◽  
1977 ◽  
Vol 27 (9) ◽  
pp. 511-517 ◽  
Author(s):  
K.J. Close ◽  
R.S. Vaughan-Watkins ◽  
J Yarwood
Keyword(s):  
High Vacuum ◽  
Low Pressure ◽  
Ultra High Vacuum ◽  
Vacuum System

scholarly journals Why Pressure Scales Cause So Much Confusion

1993 ◽  
Vol 1 (8) ◽  
pp. 5-6
Author(s):  
Anthony D. Buonaquisti
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Ambient Pressure ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Scanning Auger Microprobe ◽  
The Mean ◽  
Scanning Electron

Pressure scales can be extremely confusing to new operators. This is not surprising. To my mind, there are three primary areas of confusion.Firstly, the pressure of gas inside an instrument changes over many orders of magnitude during pumpdown. The change is about 9 orders of magnitude for a traditional Scanning Electron Microscope and about 13 orders of magnitude for an ultra-high vacuum instrument such as a Scanning Auger Microprobe.To give an idea about the scale of change involved in vacuum, consider that the change in going from ambient pressure to that inside a typical ultra high vacuum system is like comparing one meter with the mean radius of the planet Pluto's orbit. The fact is that we don't often get to play with things on that scale. As a consequence, many of us have to keep reminding ourselves that 1 X 10-3 is one thousand times the value of 1 X 10-6 - not twice the value.

scholarly journals Optical contamination control in the Advanced LIGO ultra-high vacuum system

2013 ◽  
Author(s):  
Margot H. Phelps ◽  
Kaitlin E. Gushwa ◽  
Calum I. Torrie
Keyword(s):  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Contamination Control

Development of an ultra-high vacuum system for space application

Vacuum ◽  
2004 ◽  
Vol 73 (2) ◽  
pp. 243-248 ◽  
Author(s):  
F. Grangeon ◽  
C. Monnin ◽  
M. Mangeard ◽  
D. Paulin
Keyword(s):  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Space Application

scholarly journals Enhanced Ionic Conduction at the Film/Substrate Interface in LiI Thin Films Grown on Sapphire(0001)

1993 ◽  
Vol 318 ◽  
Author(s):  
D. Lubben ◽  
F. A. Modine
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Ionic Conduction ◽  
High Vacuum ◽  
Dislocation Motion ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Substrate Interface ◽  
Interdigital Electrodes ◽  
Film Substrate

ABSTRACTThe ionic conductivity of LiI thin films grown on sapphire(0001) substrates has been studied in situ during deposition as a function of film thickness and deposition conditions. LiI films were produced at room temperature by sublimation in an ultra-high-vacuum system. The conductivity of the Lil parallel to the film/substrate interface was determined from frequency-dependent impedance measurements as a function of film thickness using Au interdigital electrodes deposited on the sapphire surface. The measurements show a conduction of ∼5 times the bulk value at the interface which gradually decreases as the film thickness is increased beyond 100 nm. This interfacial enhancement is not stable but anneals out with a characteristic log of time dependence. Fully annealed films have an activation energy for conduction (σT) of ∼0.47 ± .03 eV, consistent with bulk measurements. The observed annealing behavior can be fit with a model based on dislocation motion which implies that the increase in conduction near the interface is not due to the formation of a space-charge layer as previously reported but to defects generated during the growth process. This explanation is consistent with the behavior exhibited by CaF2 films grown under similar conditions.

Analysis Of Sige Fet Device Structures On Silicon-on-sapphire Substrates by X-Ray Diffraction

1998 ◽  
Vol 533 ◽  
Author(s):  
P. M. Mooney ◽  
J. O. Chu ◽  
J. A. Ott ◽  
J. L. Jordan-Sweet ◽  
B. S. Meyerson ◽  
...  
Keyword(s):  
Field Effect Transistors ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Device Fabrication ◽  
Ultra High Vacuum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Wafer Cleaning ◽  
Device Structures

AbstractSi/Si1-xGex, heterostructures on improved silicon-on-sapphire substrates were grown epitaxially by ultra-high vacuum chemical vapor deposition for application as p-channel field effect transistors. High-resolution triple-axis x-ray diffraction was used to analyze these structures quantitatively and to evaluate the effects of device fabrication processes on them. Out-;diffusion of Ge from the Si1-xGex, quantum well was observed after fabrication as was the change in thickness of the Si cap layer due to wafer cleaning and gate oxidation at 875 °C

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