New Developments in the Field of High Performance Turbo Molecular Pumps for the Production of Oil-Free High and Ultra High Vacuum

1974 ◽  
Vol 13 (S1) ◽  
pp. 5
Author(s):  
Jörgen Henning
Keyword(s):  
High Performance ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
New Developments

SiGe Heterojunction Bipolar Transistors

1991 ◽  
Vol 220 ◽  
Author(s):  
Maurizio Arienzo ◽  
James H. Comfort ◽  
Emmanuel F. Crabbé ◽  
David L. Marame ◽  
Subramanian S. Iyer ◽  
...  
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Layer Growth ◽  
Bipolar Transistors ◽  
Ultra High Vacuum ◽  
Ring Oscillator ◽  
Trade Offs

ABSTRACTStrained layer growth of SiGe on Si by either Molecular Beam Epitaxy (MBE) or various methods of Chemical Vapor Deposition (CVD), including Limited Reaction Processing (LRP) and Ultra High Vacuum CVD (UHV/CVD) have been used to realize narrow bandgap base double heterojunction bipolar transistors (HBTs). This review paper will focus on the fabrication of high performance transistors, and on the material and process challenges facing the implementation of SiGe HBT technology. In particular, the use of SiGe alloys for bandgap engineering of bipolar devices and the development of self-aligned, epitaxial base bipolar device structures will be discussed, including the most recent accomplishment of 75 GHz ƒr heterojunction bipolar transistors, and the record sub-25 ps EC L ring oscillator delay. The design flexibility and trade-offs offered by SiGe heterojunction technology, like junction field/capacitance control, liquid nitrogen operation and complementary processes, arc also reviewed, to assess the leverage of a SiGe base bipolar technology in high speed circuits.

scholarly journals Group III-Nitrides and Their Hybrid Structures for Next-Generation Photodetectors

2021 ◽  
Author(s):  
Deependra Kumar Singh ◽  
Basanta Kumar Roul ◽  
Karuna Kar Nanda ◽  
Saluru Baba Krupanidhi
Keyword(s):  
High Performance ◽  
High Vacuum ◽  
Group Iii Nitrides ◽  
Ultra High Vacuum ◽  
Hybrid Structures ◽  
The Novel ◽  
Nitride Semiconductors ◽  
Next Generation ◽  
High Quality ◽  
Group Iii

In the last few decades, there has been a phenomenal rise and evolution in the field of III–Nitride semiconductors for optoelectronic applications such as lasers, sensors and detectors. However, certain hurdles still remain in the path of designing high-performance photodetectors (PDs) based on III-Nitride semiconductors considering their device performance. Recently, a lot of progress has been achieved in devices based on the high quality epilayers grown by molecular beam epitaxy (MBE). Being an ultra-high vacuum environment based-technique, MBE has enabled the realization of high-quality and highly efficient PDs which have exhibited competitive figures of merit to that of the commercial PDs. Moreover, by combining the novel properties of 2D materials with MBE-grown III-Nitrides, devices with enhanced functionalities have been realized which would pave a way towards the next-generation photonics. In the current chapter, the basic concepts about photodetection have been presented in detail, followed by a discussion on the basic properties of the III-Nitride semiconductors, and the recent advancements in the field of MBE-grown III-Nitrides-based PDs, with an emphasis on their hybrid structures. Finally, an outlook has been provided highlighting the present shortcomings as well as the unresolved issues associated with the present-day devices in this emerging field of research.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

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