Characterization of Modulation Doped Pseudomorphic AlGaAs/InGaAs/GaAs Hemt Structures by Electron Beam Electroreflectance and Photoluminescence

1989 ◽  
Vol 160 ◽  
Author(s):  
M. H. Herman ◽  
I. D. Ward ◽  
R. F. Kopf ◽  
S. J. Pearton ◽  
E. D. Jones
Keyword(s):  
Electron Beam ◽  
Gaas Substrate ◽  
Device Performance ◽  
Optical Transitions ◽  
Active Device ◽  
Algaas Layer ◽  
Strained Quantum Well ◽  
Quantum Well Layer

AbstractWe have investigated the optical transitions present in MBE-grown modulation doped pseudomorphic AlxGa1-xAs/InyGa1-yAs/ GaAs HEMT structures of 120Å InGaAs thickness, y values 0 to 0.28, and x values 0.20 to 0.30. From both 300K electron beam electroreflectance (EBER) and 4K photoluminescence (PL) measurements we observe transitions from the InGaAs strained quantum well layer. The intensity and lineshape of the InGaAs transition in both optical spectra are affected by processing temperatures, and provides an indication of the quality of the HEMT.In addition to strong, sharp features arising from the GaAs substrate and the superlattice buffer, the EBER data shows important characteristics of the AlGaAs layer which are unavailable from the PL. The latter include the presence of Franz-Keldysh oscillations, from which the crystal quality, composition, and electric field strength within the AlGaAs can be assessed. Specifically, when the growth temperatures are excessive, the disappearance of the Franz-Keldysh oscillations appears to be associated with outdiffusion of In from the strained layer, and consequent deterioration of active device performance.

Characterization of III-V Semiconductor Structures Using Electron Beam Electroreflectance (EBER) spectroscopy.

1988 ◽  
Vol 144 ◽  
Author(s):  
M. H. Herman ◽  
I. D. Ward ◽  
S. E. Buttrill ◽  
G. L. Francke
Keyword(s):  
Electron Beam ◽  
Quantum Well ◽  
Quantum Wells ◽  
Sample Surface ◽  
Band Gap Energy ◽  
Quantum Well Structures ◽  
Resonant States

ABSTRACTEBER is a form of modulated reflectance spectroscopy in which a low energy electron beam alters the sample surface potential. For III-V semiconductors, the spectra are characteristic of electroreflectance, including excitonic, interband, and impurity transitions. The study of these transitions provides accurate estimations of band gaps in bulk and thick film samples. Measurements of the band gap energy in compounds such as AlxGa1-xAs provide highly precise evaluations of their composition.Additionally, EBER spectra of quantum well structures and heterojunctions provide useful information about the composition and quality of materials and interfaces. For quantum wells, detected features suggest the presence of allowed, disallowed, and resonant states. In EBER spectra of HEMT structures, peaks are apparent resulting from transitions between the valence band and the states in which the electrons are confined. We present examples of EBER determination of AlGaAs composition, single GaAs/AlGaAs quantum well evaluation, and HEMT characterization.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

A very rapid in situ Kikuchi technique to determine relative crystal misorientation

1988 ◽  
Vol 46 ◽  
pp. 830-831
Author(s):  
J. I. Bennetch
Keyword(s):  
Electron Beam ◽  
Analytical Techniques ◽  
Superplastic Forming ◽  
The Other ◽  
Kikuchi Pattern ◽  
Kikuchi Line ◽  
Line Analysis

In a recent study of the superplastic forming (SPF) behavior of certain Al-Li-X alloys, the relative misorientation between adjacent (sub)grains proved to be an important parameter. It is well established that the most accurate way to determine misorientation across boundaries is by Kikuchi line analysis. However, the SPF study required the characterization of a large number of (sub)grains in each sample to be statistically meaningful, a very time-consuming task even for comparatively rapid Kikuchi analytical techniques.In order to circumvent this problem, an alternate, even more rapid in-situ Kikuchi technique was devised, eliminating the need for the developing of negatives and any subsequent measurements on photographic plates. All that is required is a double tilt low backlash goniometer capable of tilting ± 45° in one axis and ± 30° in the other axis. The procedure is as follows. While viewing the microscope screen, one merely tilts the specimen until a standard recognizable reference Kikuchi pattern is centered, making sure, at the same time, that the focused electron beam remains on the (sub)grain in question.

Particle characterization of CVD tungsten metallization for 64 MBIT DRAM

1991 ◽  
Vol 49 ◽  
pp. 896-897
Author(s):  
Marylyn Bennett-Lilley ◽  
Thomas T.H. Fu ◽  
David D. Yin ◽  
R. Allen Bowling
Keyword(s):  
Chemical Vapor ◽  
Device Performance ◽  
Particle Characterization ◽  
Particle Generation ◽  
Tungsten Hexafluoride ◽  
Homogeneous Particle ◽  
Multiple Levels ◽  
Circuit Density ◽  
Sources Of Contamination

Chemical Vapor Deposition (CVD) tungsten metallization is used to increase VLSI device performance due to its low resistivity, and improved reliability over other metallization schemes. Because of its conformal nature as a blanket film, CVD-W has been adapted to multiple levels of metal which increases circuit density. It has been used to fabricate 16 MBIT DRAM technology in a manufacturing environment, and is the metallization for 64 MBIT DRAM technology currently under development. In this work, we investigate some sources of contamination. One possible source of contamination is impurities in the feed tungsten hexafluoride (WF6) gas. Another is particle generation from the various reactor components. Another generation source is homogeneous particle generation of particles from the WF6 gas itself. The purpose of this work is to investigate and analyze CVD-W process-generated particles, and establish a particle characterization methodology.

Methods to Monitor and Improve the Performance of Specimen Holders for Transmission Electron Cryomicroscopy

1996 ◽  
Vol 54 ◽  
pp. 454-455
Author(s):  
B. L. Armbruster ◽  
B. Kraus ◽  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Quality Of Data ◽  
Electron Cryomicroscopy ◽  
Thermal Equilibration ◽  
Transmission Electron ◽  
Electron Microscopes

One goal in electron microscopy of biological specimens is to improve the quality of data to equal the resolution capabilities of modem transmission electron microscopes. Radiation damage and beam- induced movement caused by charging of the sample, low image contrast at high resolution, and sensitivity to external vibration and drift in side entry specimen holders limit the effective resolution one can achieve. Several methods have been developed to address these limitations: cryomethods are widely employed to preserve and stabilize specimens against some of the adverse effects of the vacuum and electron beam irradiation, spot-scan imaging reduces charging and associated beam-induced movement, and energy-filtered imaging removes the “fog” caused by inelastic scattering of electrons which is particularly pronounced in thick specimens.Although most cryoholders can easily achieve a 3.4Å resolution specification, information perpendicular to the goniometer axis may be degraded due to vibration. Absolute drift after mechanical and thermal equilibration as well as drift after movement of a holder may cause loss of resolution in any direction.

Physicochemical and bacteriological characterization of hospital effluents and their impact on the environment

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Human Health ◽  
Fecal Coliforms ◽  
Chemical Pollution ◽  
Hospital Effluents ◽  
Biological Contaminants ◽  
Almost All ◽  
Direct Discharge ◽  
Significant Chemical

Liquid effluents discharged by hospitals may contain chemical and biological contaminants whose main source is the different substances used for the treatment of patients. This type of rejection can present a sanitary potentially dangerous risk for human health and can provoke a strong degradation of diverse environmental compartments mainly water and soils. The present study focuses on the quality of the liquid effluents of Hassani Abdelkader’s hospital of Sidi Bel-Abbes (West of Algeria). The results reveal a significant chemical pollution (COD: 879 mgO2/L, BOD5: 850 mgO2/L, NH4+ : 47.9 mg/l, NO2- : 4.2 mg/l, NO3- : 56.8 mg/l with respect to WHO standard of 90 mgO2/L, 30 mgO2/L, 0.5 mg/l, 1 mg/l and 1 mg/l respectively). However, these effluents are biodegradable since the ratio COD/BOD5 do not exceeded the value of 2 in almost all samples. The presence of pathogen germs is put into evidence such as pseudomonas, the clostridium, the staphylococcus, the fecal coliforms and fecal streptococcus. These results show that the direct discharge of these effluents constitutes a major threat to human health and the environment.

Investigation of Die Tilting of Packages with Single and Multi-chips

2018 ◽  
Author(s):  
Lo Chea Wee ◽  
Tan Sze Yee ◽  
Gan Sue Yin ◽  
Goh Cin Sheng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Optical Microscopy ◽  
Device Performance ◽  
Electronic Components ◽  
Area Of Interest ◽  
On Chip ◽  
Scanning Electron

Abstract Advanced package technology often includes multi-chips in one package to accommodate the technology demand on size & functionality. Die tilting leads to poor device performance for all kinds of multi-chip packages such as chip by chip (CbC), chip on chip (CoC), and the package with both CbC and CoC. Traditional die tilting measured by optical microscopy and scanning electron microscopy has capability issue due to wave or electron beam blocking at area of interest by electronic components nearby. In this paper, the feasibility of using profilemeter to investigate die tilting in single and multi-chips is demonstrated. Our results validate that the profilemeter is the most profound metrology for die tilting analysis especially on multi-chip packages, and can achieve an accuracy of <2μm comparable to SEM.

Characterization of AA7075/AA5356 gradient transition zone in an electron beam wire-feed additive manufactured sample

2021 ◽  
Vol 172 ◽  
pp. 110867
Author(s):  
V. Utyaganova ◽  
A. Filippov ◽  
S. Tarasov ◽  
N. Shamarin ◽  
D. Gurianov ◽  
...  
Keyword(s):  
Electron Beam ◽  
Transition Zone ◽  
Feed Additive ◽  
Wire Feed
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