The Characterization of Intentional Dopants in HgCdTe using Sims, Hall-Effect, and C-V Measurements

1985 ◽  
Vol 48 ◽  
Author(s):  
L. E. Lapides ◽  
R. L. Whitney ◽  
C. A. Crosson
Keyword(s):  
Electrical Properties ◽  
Hall Effect ◽  
Secondary Ion Mass Spectrometry ◽  
Dopant Concentration ◽  
Relative Sensitivity ◽  
Base Layer ◽  
Layer Structures ◽  
Dopant Atoms ◽  
Dopant Profiles

ABSTRACTThe properties of selected dopants in liquid-phase epitaxial (LPE) layers of HgCdTe have been studied using secondary ion mass spectrometry (SIMS), Hall-effect, and capacitance-voltage (C-V) measurements. The layers were grown from Hg-rich melts on {111}-oriented CdTe and CdZnTe single-crystal substrates. Diodes, for the C-V measurements, were homojunctions formed by ion implantation or heterojunctions formed by the growth of a second layer on the base layer. Dopant concentration distributions in both single- and double-layer structures were characterized by SIMS and C-V measurements. The dopant profiles measured by SIMS were quantified using relative sensitivity factors calculated from ion implanted impurity profiles measured on standard reference samples. Using specialized SIMS techniques, such as molecular ion spectrometry, As concentrations as low as 2 × 1015 cm−3 have been measured. In the HgCdTe:In/HgCdTe:As system minimal dopant interdiffusion is observed in SIMS profiles. The growth of the second layer has insignificant effect on the As distribution in the base layer, and C-V data indicate that the electrical properties change only slightly. Carrier types and concentrations were determined by Hall effect and C-V measurements. Good agreement between dopant concentrations and carrier concentrations was observed, indicating 100% activation of the dopant atoms, for all dopants studied. Examples of implant calibration profiles, dopant concentration distributions, carrier concentration vs temperature measurements, and 1/C2 vs V data are presented, along with graphs and tables comparing dopant profiles with electrical properties.

The Use of SIMS and SEM for the Characterization of Individual Particles with a Matrix Originating from a Nuclear Weapon

2007 ◽  
Vol 13 (3) ◽  
pp. 179-190 ◽  
Author(s):  
Ylva Ranebo ◽  
Mats Eriksson ◽  
Gabriele Tamborini ◽  
Nedialka Niagolova ◽  
Olivier Bildstein ◽  
...  
Keyword(s):  
Nuclear Weapons ◽  
Secondary Ion Mass Spectrometry ◽  
Isotopic Ratio ◽  
Relative Sensitivity ◽  
Mass Range ◽  
Morphological Properties ◽  
Sensitivity Factor ◽  
Surface Layers ◽  
X Ray

The application of scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) for characterization of mixed plutonium and uranium particles from nuclear weapons material is presented. The particles originated from the so-called Thule accident in Greenland in 1968. Morphological properties have been studied by SEM and two groups were identified: a “popcorn” structure and a spongy structure. The same technique, coupled with an energy-dispersive X-ray (EDX) spectrometer, showed a heterogeneous composition of Pu and U in the surface layers of the particles. The SIMS depth profiles revealed a varying isotopic composition indicating a heterogeneous mixture of Pu and U in the original nuclear weapons material itself. The depth distributions agree with synchrotron-radiation-based μ-XRF (X-ray fluorescence microprobe) measurements on the particle (Eriksson, M., Wegryzynek, D., Simon, R., & Chinea-Cano, E., in prep.) when a SIMS relative sensitivity factor for Pu to U of 6 is assumed. Different SIMS identified isotopic ratio groups are presented, and the influence of interferences in the Pu and U mass range are estimated. The study found that the materials are a mixture of highly enriched235U (235U:238U ratio from 0.96 to 1.4) and so-called weapons grade Pu (240Pu:239Pu ratio from 0.028 to 0.059) and confirms earlier work reported in the literature.

Ion Yield, Sputter Rate, and Sims Matrix Effects in Quantitative Analysis of (AlxGa1−x)0.5N0.5

1998 ◽  
Vol 510 ◽  
Author(s):  
D.L. Lefforge ◽  
Y.L. Chang ◽  
M. Ludowise ◽  
E.L. Allen
Keyword(s):  
Aluminum Gallium Nitride ◽  
Secondary Ion Mass Spectrometry ◽  
Matrix Effects ◽  
Rutherford Backscattering Spectrometry ◽  
Relative Sensitivity ◽  
Epitaxial Films ◽  
Sensitivity Factor ◽  
Primary Composition ◽  
Secondary Ion

AbstractAluminum gallium nitride (AlGaN) material is used in GaN-based electronic and optoelectonic devices. The Al and Ga ratio can be adjusted to produce material with different compositions and electronic properties. In this set of experiments epitaxial films of (AlxGa1−x)0.5N0.5 with x ranging from 0 to 1 were investigated. Primary composition was determined with Rutherford backscattering spectrometry (RBS). From secondary ion mass spectrometry (SIMS) profiles a correlation of secondary ion counts was made to RBS determinations of primary composition. The SIMS data was also used to determine sputter rate and the relative sensitivity factor (RSF) of O, Mg and Si in (AlxGa1−x)0.5N0.5 material. The correlation of SIMS data with RBS and knowledge of the sputter rate and RSF dependence on composition are essential for the characterization of (AlxGa1−x)0.5N0.5 films

Applications of SIMS to electronic materials and devices

1992 ◽  
Vol 50 (2) ◽  
pp. 1682-1683
Author(s):  
S.F. Corcoran
Keyword(s):  
Depth Distribution ◽  
Secondary Ion Mass Spectrometry ◽  
Semiconductor Device ◽  
Electronic Materials ◽  
Profile Analysis ◽  
Semiconductor Industry ◽  
Small Diameter ◽  
Depth Resolution ◽  
Detection Sensitivity

Over the past decade secondary ion mass spectrometry (SIMS) has played an increasingly important role in the characterization of electronic materials and devices. The ability of SIMS to provide part per million detection sensitivity for most elements while maintaining excellent depth resolution has made this technique indispensable in the semiconductor industry. Today SIMS is used extensively in the characterization of dopant profiles, thin film analysis, and trace analysis in bulk materials. The SIMS technique also lends itself to 2-D and 3-D imaging via either the use of stigmatic ion optics or small diameter primary beams.By far the most common application of SIMS is the determination of the depth distribution of dopants (B, As, P) intentionally introduced into semiconductor materials via ion implantation or epitaxial growth. Such measurements are critical since the dopant concentration and depth distribution can seriously affect the performance of a semiconductor device. In a typical depth profile analysis, keV ion sputtering is used to remove successive layers the sample.

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

scholarly journals Chemical Evaluation of Eumelanin Maturation by ToF-SIMS and Alkaline Peroxide Oxidation HPLC Analysis

2020 ◽  
Vol 22 (1) ◽  
pp. 161
Author(s):  
Martin Jarenmark ◽  
Peter Sjövall ◽  
Shosuke Ito ◽  
Kazumasa Wakamatsu ◽  
Johan Lindgren
Keyword(s):  
Molecular Structure ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Characterization ◽  
Experimental Treatment ◽  
Negative Ion ◽  
Pressure Treatment ◽  
Peroxide Oxidation ◽  
Specific Chemical ◽  
Tof Sims

Residual melanins have been detected in multimillion-year-old animal body fossils; however, confident identification and characterization of these natural pigments remain challenging due to loss of chemical signatures during diagenesis. Here, we simulate this post-burial process through artificial maturation experiments using three synthetic and one natural eumelanin exposed to mild (100 °C/100 bar) and harsh (250 °C/200 bar) environmental conditions, followed by chemical analysis employing alkaline hydrogen peroxide oxidation (AHPO) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Our results show that AHPO is sensitive to changes in the melanin molecular structure already during mild heat and pressure treatment (resulting, e.g., in increased C-C cross-linking), whereas harsh maturation leads to extensive loss of eumelanin-specific chemical markers. In contrast, negative-ion ToF-SIMS spectra are considerably less affected by mild maturation conditions, and eumelanin-specific features remain even after harsh treatment. Detailed analysis of ToF-SIMS spectra acquired prior to experimental treatment revealed significant differences between the investigated eumelanins. However, systematic spectral changes upon maturation reduced these dissimilarities, indicating that intense heat and pressure treatment leads to the formation of a common, partially degraded, eumelanin molecular structure. Our findings elucidate the complementary nature of AHPO and ToF-SIMS during chemical characterization of eumelanin traces in fossilized organismal remains.

A Sims Study of Electroluminescent Phosphors: SrS:Cu

1999 ◽  
Vol 560 ◽  
Author(s):  
Lily H. Zhang ◽  
Larry Wang ◽  
Wusheng Tong ◽  
YongBao Xin
Keyword(s):  
Material Characterization ◽  
Secondary Ion Mass Spectrometry ◽  
Dopant Concentration ◽  
Thermal Quenching ◽  
Areal Density ◽  
Device Performance ◽  
Cell Temperature ◽  
Co Doping ◽  
Doping Effects ◽  
Secondary Ion

ABSTRACTThis study has used secondary ion mass spectrometry (SIMS) as a technique for thin film EL material characterization. It has shown that the Cu dopant concentration in the SrS films directly correlates with the luminescent brightness of the EL devices. A series of SrS:Cu,Y were grown using MBE to study the Y co-doping effects. It has been found that Y peak concentration and areal density in the SrS increased as the Y evaporation cell temperature was increased. The maximum PL intensity was found in the sample grown in the middle of the Y cell temperature range used. The Y co-doping has shown to reduce the thermal quenching effects in SrS EL devices. Therefore, in this series of samples, a good correlation has been found between Y and Cu concentration and the EL device performance characteristics.

Characterization of a Hall Effect Thruster Using Thermal Imaging

2007 ◽  
Author(s):  
James Tomaszewski ◽  
Richard Branam ◽  
William Hargus ◽  
Taylor Matlock
Keyword(s):  
Hall Effect ◽  
Thermal Imaging ◽  
Hall Effect Thruster
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