Rapid Thermal Diffusion of Zinc In GaAs

1987 ◽  
Vol 92 ◽  
Author(s):  
T.S. Kalkur ◽  
Y.C. Lu ◽  
C.A. Paz de Araujo
Keyword(s):  
Thermal Diffusion ◽  
Ohmic Contacts ◽  
Low Voltage ◽  
Hole Concentration ◽  
Silica Film ◽  
Transmission Line Method ◽  
Van Der Pauw ◽  
Rapid Thermal Diffusion ◽  
Secondary Ion ◽  
Voltage Scanning

ABSTRACTRapid thermal diffusion of zinc into semi-insulating GaAs from spin-on zinc silica film is investigated. The rapid thermal diffusion is performed for various diffusion times (5 to 25 sec) and temperatures (800° to 950° C) with tungstenhalogen lamps as the heat source. The sheet resistivity, surface hole concentration and mobility of these zinc diffused layers as measured by Van der Pauw technique shows the formation of shallow p+ layer. The surface morphology of these diffused layers are observed in a low voltage Scanning Electron Microscope (SEM) and the depth profile of diffused impurities are determined by Secondary Ion Mass Spectroscopy (SIMS). Nonalloyed ohmic contacts are formed on these zinc diffused layers and the contact resistivity is determined by the Transmission Line Method (TLM).

Boron Doping using Proximity Rapid Thermal Diffusion from Spin-on-Dopants

1994 ◽  
Vol 342 ◽  
Author(s):  
M. Rastogi ◽  
W. Zagozdzon-Wosik ◽  
F. Romero-Borja ◽  
J. M. Heddleson ◽  
R. Beavers ◽  
...  
Keyword(s):  
Thermal Diffusion ◽  
Process Variables ◽  
Dopant Incorporation ◽  
Boron Doped ◽  
Doping Technique ◽  
Rapid Thermal Diffusion ◽  
P Type ◽  
Temperature Time ◽  
Secondary Ion ◽  
Dopant Source

ABSTRACTProximity rapid thermal diffusion (RTD) has been investigated as a doping technique for p-type boron doped junctions. The efficiency of RTD has been studied as a function of process variables (temperature, time, and ambient) and evaluated based on sheet resistance measurements, secondary ion mass spectroscopy (SIMS), spreading resistance (SR), and Fourier transmission infrared absorption (FTIR) in a spin-on-dopant source (SOD). The doping efficiency in source wafers is controlled by different mechanism than in processed wafers. Strong influence of dopant incorporation in the processed wafers on oxygen content in the diffusion ambient is observed especially at low diffusion temperatures.

Rapid thermal diffusion and ohmic contacts using zinc in GaAs and GaAlAs

1987 ◽  
Vol 51 (25) ◽  
pp. 2118-2120 ◽  
Author(s):  
Sandip Tiwari ◽  
Jeffrey Hintzman ◽  
Alessandro Callegari
Keyword(s):  
Thermal Diffusion ◽  
Ohmic Contacts ◽  
Rapid Thermal Diffusion

Carbon Doping of GaAs by OMVPE Using CC14: A Comparison of Gallium and Arsenic Precursors

1991 ◽  
Vol 240 ◽  
Author(s):  
W. S. Hob Son
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Hole Concentration ◽  
Carbon Doping ◽  
Carbon Incorporation ◽  
C Doping ◽  
Van Der Pauw ◽  
Secondary Ion ◽  
Dopant Source ◽  
Very High

ABSTRACTThe carbon doping properties of GaAs with carbon tetrachloride as the dopant source were examined using trimethylgallium (TMGa) or triethylgallium (TEGa) as the gallium precursors and arsine or tertiarybutylarsine (TBAs) as the arsenic precursors. Secondary ion mass spectrometry (SIMS) and Hall measurements (van der Pauw method) were used to characterize the epitaxial GaAs:C layers. Very high C-doping concentrations (∼1020 cm−3) could be obtained with either TMGa and TEGa. The use of TBAs instead of AsH3 led to a significant reduction in carbon incorporation, by approximately a factor of 5–10 per mole of As precursor, over the temperature range examined (520°C - 700°C). Hydrogen at significant concentrations (0.5 – 6 × 1019 cm−3) was detected by SIMS in GaAs:C layers grown at ≤550°C utilizing all four combinations of Ga/As precursors and suggested the presence of electrically inactive C-H complexes. A post-growth anneal under helium at 550°C for 60s of these samples resulted in a 50–100% increase in hole concentration by driving out the hydrogen.

Low Resistance Non-Transparent ohmic Pt-contacts on p-GaN

2001 ◽  
Vol 693 ◽  
Author(s):  
Andreas Weimar ◽  
Stefan Bader ◽  
Georg Brüderl ◽  
Volker Kümmler
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Hole Concentration ◽  
Blue Laser ◽  
Specific Contact Resistance ◽  
Low Resistance ◽  
Specific Contact ◽  
Device Operation ◽  
Secondary Ion ◽  
Resistance Value

AbstractThe metal – p-GaN junction for low resistance ohmic contacts is still a challenge to be applied in GaN-based opto electronics as well as in power and high frequency devices. Currently, we try to improve the performance of our blue laser diodes. In order to decrease heat generation during device operation it is necessary to ensure as small contact resistances as possible.In this work, we achieved a specific contact resistance value of RC = 1.8 ± 1.7. 10-5 Ωcm2 for Pt-contacts on MOVPE-grown p-GaN. The Pt-layers were deposited by e-beam and thermally assisted vacuum evaporation after a standard cleaning process. For evaluation of Rc we used optimised circular TLM test patterns defined by photolithography. Best contacts were formed by annealing in Nitrogen athmosphere at 500°C.We also investigated the dependence of the contact resistance on the Mg doping concentration. Therefore p-GaN layers with different Mg-concentrations were grown on SiC-substrates and Pt-contacts were processed. For those samples, we investigated the Mg-concentrations, verified by secondary ion mass spectroscopy (SIMS), the hole concentrations and mobilities in dependence of C(Mg), which we obtained from HALL-measurements, and the contact and sheet resistances, measured by circular TLM measurements.The experiments showed that the optimum Mg-concentration for low contact resistances is higher than 2 1019 cm-3 which was found to provide a maximum hole concentration near 7 1017 cm-3. The influence of self-compensation in p-GaN in bulk and near interfaces will be discussed.

Investigation of Proximity Rtd for Submicron Junctions in Vlsi Si Devices

1993 ◽  
Vol 303 ◽  
Author(s):  
W. Zagozdzon-Wosik ◽  
P. Grabiec ◽  
F. Romero-Borja ◽  
L. T. Wood ◽  
G. Lux
Keyword(s):  
Sheet Resistance ◽  
Thermal Diffusion ◽  
Mass Spectroscopy ◽  
Secondary Ion Mass Spectroscopy ◽  
Si Doping ◽  
Shallow Junctions ◽  
Rapid Thermal Diffusion ◽  
Kinetics Of ◽  
Secondary Ion

ABSTRACTProximity rapid thermal diffusion is presented as a doping process for fabrication of very shallow junctions. The kinetics of Si doping with B, P and As is investigated using sheet resistance measurements, secondary ion mass spectroscopy and FTIR analyses. The efficiency of doping is affected by the dopant transport in the SOD which depends on the structure and composition of the SOD.

Processing of human melanoma cells for correlative TEM, LVSEM, and LM

1991 ◽  
Vol 49 ◽  
pp. 106-107
Author(s):  
Marek Malecki ◽  
J. Victor Small ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Fluorescent Microscopy ◽  
Blood Stream ◽  
Surface Topology ◽  
Integrin Receptors ◽  
Transmission Electron ◽  
Develop Technology ◽  
Voltage Scanning ◽  
Mechanisms Of Adhesion

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Actin filaments in two spermatozoa of crustacea decapoda

1990 ◽  
Vol 48 (3) ◽  
pp. 70-71
Author(s):  
E. Dupré ◽  
G. Schatten
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Low Voltage ◽  
Active Role ◽  
Main Body ◽  
Robinson Crusoe ◽  
Decapod Crustaceans ◽  
Actual Participation ◽  
Voltage Scanning ◽  
Scanning Electron

Sperm of decapod crustaceans are formed by a round or cup-shaped body, a complex acrosome and one a few appendages emerging from the main body. Although this sperm does not have motility, it has some components of the cytoskeleton like microtubules, which are found inside the appendages. Actin filaments have been found in the spike of penaeidae sperms. The actual participation of the crustacean decapod sperm cytoskeleton during fertilization is not well understood. Actin is supposed to play an active role in drawing the penaeidae shrimp sperm closer to the egg after bending of the spike. The present study was aimed at the localization of actin filaments in sperm of the Robinson Crusoe island lobster, Jasus frontalis and in the crayfish Orconectes propincus, by fluorescent probes and low voltage scanning electron microscopy.

Recent developments in low-voltage SEM of polymers

1993 ◽  
Vol 51 ◽  
pp. 866-867
Author(s):  
S.J. Krause ◽  
W.W. Adams
Keyword(s):  
Low Voltage ◽  
Chromatic Aberration ◽  
Thermal Electron ◽  
Analytical Technique ◽  
Recent Developments ◽  
Beam Currents ◽  
New Generation ◽  
First Time ◽  
Voltage Scanning ◽  
Beam Damage

Over the past decade low voltage scanning electron microscopy (LVSEM) of polymers has evolved from an interesting curiosity to a powerful analytical technique. This development has been driven by improved instrumentation and in particular, reliable field emission gun (FEG) SEMs. The usefulness of LVSEM has also grown because of an improved theoretical and experimental understanding of sample-beam interactions and by advances in sample preparation and operating techniques. This paper will review progress in polymer LVSEM and present recent results and developments in the field.In the early 1980s a new generation of SEMs produced beam currents that were sufficient to allow imaging at low voltages from 5keV to 0.5 keV. Thus, for the first time, it became possible to routinely image uncoated polymers at voltages below their negative charging threshold, the "second crossover", E2 (Fig. 1). LVSEM also improved contrast and reduced beam damage in sputter metal coated polymers. Unfortunately, resolution was limited to a few tenths of a micron due to the low brightness and chromatic aberration of thermal electron emission sources.

Low-voltage field-emission SEM of polymeric membranes for glucose biosensors

1990 ◽  
Vol 48 (3) ◽  
pp. 860-861
Author(s):  
Lorna K. Mayo ◽  
Kenneth C. Moore ◽  
Mark A. Arnold
Keyword(s):  
Glucose Sensor ◽  
Low Voltage ◽  
Glucose Sensors ◽  
Polymeric Membranes ◽  
Artificial Endocrine Pancreas ◽  
Self Monitoring ◽  
Conducting Materials ◽  
Insulin Dependent ◽  
Living Tissues ◽  
Voltage Scanning

An implantable artificial endocrine pancreas consisting of a glucose sensor and a closed-loop insulin delivery system could potentially replace the need for glucose self-monitoring and regulation among insulin dependent diabetics. Achieving such a break through largely depends on the development of an appropriate, biocompatible membrane for the sensor. Biocompatibility is crucial since changes in the glucose sensors membrane resulting from attack by orinter action with living tissues can interfere with sensor reliability and accuracy. If such interactions can be understood, however, compensations can be made for their effects. Current polymer technology offers several possible membranes that meet the unique chemical dynamics required of a glucose sensor. Two of the most promising polymer membranes are polytetrafluoroethylene (PTFE) and silicone (Si). Low-voltage scanning electron microscopy, which is an excellent technique for characterizing a variety of polymeric and non-conducting materials, 27 was applied to the examination of experimental sensor membranes.

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