MBE Growth of Compositionally Modulated Ceramics

1987 ◽  
Vol 103 ◽  
Author(s):  
R. A. Mckee ◽  
F. A. List ◽  
F. J. Walker
Keyword(s):  
Thin Film ◽  
Growth Rate ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Mbe Growth ◽  
Compositional Modulation ◽  
Molecular Source ◽  
Constituent Elements

ABSTRACTAn ultra high vacuum system fitted with thermal effusion cells that heat 20cc of material to temperatures as high as 2000 °C is being used to synthesize thin film and multilayer ceramics from their constituent elements. A molecular source for oxygen used in conjunction with these effusion cells allows oxides of Al, Ti, Cu, and Y to be grown with compositional modulation controlling growth rate and stoichiometry.

TEM study of chemically converted SiC thin film on nanometer curved Si surface

1993 ◽  
Vol 51 ◽  
pp. 818-819
Author(s):  
A. N. Stepanova ◽  
J. Liu ◽  
K. N. Christensen ◽  
U. T. Son ◽  
K. J. Bachmann ◽  
...  
Keyword(s):  
Thin Film ◽  
Silicon Surface ◽  
Flat Surface ◽  
Mechanical Strain ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Microelectronic Devices ◽  
Vacuum Microelectronic ◽  
Field Emission Cathodes

Silicon whiskers with nanometer curvature have a variety of applications such as probes in STM and AFM, or field emission cathodes for vacuum microelectronic devices. For these and other applications it is essential to stabilize the sharply curved silicon surface during usage. Carburization of the silicon surface seems to be a very suitable solution to this problem, since SiC crystals have excellent physical properties and are chemically quite inert. There have been a number of reports of the carburization of flat surface silicon wafers by chemical reaction using both CVD and MBE methods. However, to carburize while maintaining a very sharp silicon tip is extremely difficult. It is also desirable to carburize only a very thin layer, so as to avoid excessive mechanical strain arising from the large difference (∼20%) in lattice parameters.Our carburizations were carried out in a turbo-pumped ultra-high vacuum system. The silicon specimens were oxidation sharpened and cleaned in a buffered HF solution.

The Fabrication of Thin Film NiTi Shape Memory Alloy Micro Actuator for MEMS Application

1999 ◽  
Author(s):  
John J. Gill ◽  
Ken Ho ◽  
Gregory P. Carman
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Niti Shape Memory Alloy ◽  
Cylindrical Shape ◽  
Finish Temperature

Abstract Thin film SMA (Shape memory alloy) is a useful method for MEMS (Microelectromechanical Systems) actuator. This is because the thin film has an improved frequency response compared to bulk SMA, high work density, and produces large strain. A novel two-way thin film NiTi (Nickel Titanium) shape memory alloy actuator is presented in this paper. Thin film shape memory alloy is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the deposited NiTi film are measured by residual stress measurement at temperatures from 25 ° C to 120 ° C. Test results show that the Mf (Martensite Finish Temperature) is around 60 ° C and Af (Austenite Finish Temperature) is around 110 ° C. A free standing NiTi membrane (10 mm × 10mm and 3 μm thick) is fabricated using MEMS technology. We found that a mixture of HF (Hydro Fluidic Acid), HNO3 (Nitric Acid) and DI (Deionized) water with thick photo resist mask works best for the fabrication process. The membrane is hot-shaped in different shapes such as dome shape, pyramidal shape, and cylindrical shape. Results indicate that when the temperature of the NiTi film exceeds Af, the NiTi membrane transforms into the trained hot-shape. When the temperature cools down to room temperature, the membrane returns to the initial flat shape.

Thin Film NiTi Shape Memory Alloy Microactuator With Two-Way Effect

2000 ◽  
Author(s):  
John J. Gill ◽  
Gregory P. Carman
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Frequency Response ◽  
Microelectromechanical Systems ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Niti Shape Memory Alloy ◽  
Maximum Deflection

Abstract Thin film SMA (Shape memory alloy) is a useful material for MEMS (Microelectromechanical Systems) actuator. This is because the thin film has an improved frequency response compared to bulk SMA, high work density, and produces large strain. A novel two-way thin film NiTi (Nickel Titanium) shape memory alloy actuator is presented in this paper. Thin film shape memory alloy is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the NiTi film are determined by measuring the residual stress as a function of temperature. Test results show that the Martensite-Temperature-Finish (Mf) is approximately 60° C, and the Austenite-Temperature-Finish (Af) is 110° C. A free standing NiTi membrane (12 mm × 12 mm and 2.5 μm thick) is fabricated using MEMS technology. We found that a mixture of HF (Hydro Fluoric Acid), HNO3 (Nitric Acid) and DI (Deionized) water with thick photo resist mask works best for the fabrication process. The membrane is hot-shaped into a dome shape. Results indicate that when the temperature of the NiTi film exceeds Af, the NiTi membrane transforms into the trained hot-shape. When the temperature cools down to room temperature, the membrane returns to the initial flat shape. The performance of the SMA micro actuator is characterized with a laser measurement system for deflection vs. input power and frequency response. The maximum deflection of SMA microactuator is 230 μm. The corresponding frequency responses at the maximum deflection are 30 Hz with Copper (Cu) block placed underneath the microactuator and less than 1 Hz when Plexi-glass is placed.

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
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