Ultra-high vacuum system for continuous evaporation of multilayer thin films

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.

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MAGNETIC TRANSITION IN QUASI ONE DIMENSIONAL WIRES AND THIN FILMS OF GADOLINIUM

International Journal of Modern Physics B ◽

10.1142/s0217979293001037 ◽

1993 ◽

Vol 07 (01n03) ◽

pp. 496-499

Author(s):

NAUSHAD ALI ◽

J. T. MASDEN ◽

PEGGY HILL ◽

ARTHUR CHIN

Keyword(s):

Thin Films ◽

Magnetic Transition ◽

High Vacuum ◽

Magnetic Ordering ◽

Ultra High Vacuum ◽

Vacuum System ◽

Ferromagnetic Transition ◽

Sharp Drop ◽

Cross Sectional ◽

Thin Wires

Thin wires of gadolinium metal have been fabricated using a step lithographic technique with cross-sectional areas from 0.87 × 10−11 cm 2 to 58 × 10−11 cm 2. The thin films of gadolinium were deposited in a ultra high vacuum system by thermal evaporation with the thickness of films in the range 200Å to 1200Å. Resistivity data of Gd thin wires does not show evidence of bulk transition at T c ≈ 293 K (bulk) at all. However, a phase transition manifested as a sharp drop in resistivity of Gd thin wires is observed around 20 K. Thin films of Gd deposited on glass and sapphire substrates were used to measure the magnetic properties using a SQUID magnetometer. Films of thickness > 500Å show ferromagnetic transition around 290 K (close to bulk) and a small peak in the magnetization around 20 K is also observed. For Gd films of thickness ~ 200Å there is no evidence of ferromagnetic transition, however, the magnetization data clearly shows a peak in the neighborhood of 20 K. It appears that in the case of very thin films and thin wires of Gd we are observing a magnetic transition around 20 K. This transition may be due to magnetic ordering of the surface which has a transition temperature much smaller than the bulk ferromagnetic T c of 293 K.

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An Oil-free Ultra-high Vacuum System for the Deposition of Thin Films

Vacuum Technology Transactions ◽

10.1016/b978-1-4831-9852-1.50020-7 ◽

2013 ◽

pp. 66-71

Author(s):

H.L. CASWELL

Keyword(s):

Thin Films ◽

High Vacuum ◽

Ultra High Vacuum ◽

Vacuum System

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An oil free ultra high vacuum system for the deposition of thin films by Hollis L. Caswell, International Business Machines Corporation, Research Laboratory, Poughkeepsie, New York

Vacuum ◽

10.1016/0042-207x(59)90436-1 ◽

1959 ◽

Vol 9 (5-6) ◽

pp. 298

Keyword(s):

Thin Films ◽

New York ◽

International Business ◽

Research Laboratory ◽

High Vacuum ◽

Ultra High Vacuum ◽

Vacuum System

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TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151428 ◽

1993 ◽

Vol 51 ◽

pp. 1118-1119

Author(s):

Pamela F. Lloyd ◽

Scott D. Walck

Keyword(s):

Thin Films ◽

Sample Preparation ◽

Room Temperature ◽

High Vacuum ◽

Pulsed Laser ◽

Ultra High Vacuum ◽

Wear Testing ◽

Preparation Technique ◽

Cross Sectional ◽

Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

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The Growth of Semiconductor Thin Films Studied by RHEED

Australian Journal of Physics ◽

10.1071/ph900583 ◽

1990 ◽

Vol 43 (5) ◽

pp. 583

Author(s):

GL Price

Keyword(s):

Thin Films ◽

Surface Science ◽

High Vacuum ◽

High Energy ◽

Ultra High Vacuum ◽

Large Area ◽

Growth Modes ◽

Semiconductor Thin Films ◽

Wide Range ◽

Recent Developments

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

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Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

International Journal of Molecular Sciences ◽

10.3390/ijms22136880 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6880

Author(s):

Zilong Wang ◽

Minlong Tao ◽

Daxiao Yang ◽

Zuo Li ◽

Mingxia Shi ◽

...

Keyword(s):

Thin Films ◽

Self Assembly ◽

High Vacuum ◽

Ultra High Vacuum ◽

Scanning Tunneling ◽

Kagome Lattice ◽

Tunneling Microscopy ◽

Kagomé Lattice ◽

Temperature Scanning ◽

C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

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