Modification of high purity N-type silicon surfaces by antimony delta doping for detector applications
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silicon n-type silicon detectors charge coupled de↗
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Investigation of the Antimony-Rich Part of the Ru-Sb System
The Ru-Sb phase diagram is not available and very little informations is known about this system.
phase diagram Differential ThermalAnalysis (DTA) d↗
Minority Carrier Lifetime and Photoluminescence Studies of Antimony-Based Superlattices
In this paper, we have used the OMR technique to study the minority carrier lifetimes in three InAs/GaSb-photoluminescence (PL) structures with different number of periods in the absorber: 300, 400 and 600 periods respectively. The feasibility of using a visible 643 nm laser source with short penetration depth for lifetime measurements was studied by comparing the achieved results to measurements performed on the same samples with a 1550 nm IR laser source, which penetrates much deeper into the sample. Despite the differences in excitation wavelengths and penetration depths, the results from both measurements were very similar. This indicates that the diffusion length is long enough to facilitate a homogeneous distribution of excess carriers in the material.
photodetector↗
Venus: Halide cloud condensation and volatile element inventories
Several Venus cloud condensates, including A12C16 as well as halides, oxides and sulfides of arsenic and antimony, are assessed for their thermodynamic and geochemical plausibility. Aluminum chloride can confidently be ruled out, and condensation of arsenic sulfides on the surface will cause arsenic compounds to be too rare to produce the observed clouds. Antimony may conceivably be sufficiently volatile, but the expected molecular form is gaseous SbS, not the chloride. Arsenic and antimony compounds in the atmosphere will be regulated at very low levels by sulfide precipitation, irrespective of the planetary inventory of As and Sb. Thus the arguments for a volatile-deficient origin for Venus based on the depletion of water and mercury (relative to Earth) cannot be tested by a search for atmospheric arsenic or antimony.
Lewis, J. S.↗
Use of radiation in preparative chemistry
A summary and updating of previous work on the use of radiation chemistry for the preparation of pure materials are presented. Work was chiefly concerned with the reduction of metal salts in solution to the free metal using 2 MeV electrons. Metals deposited from aqueous solution are copper, silver, zinc, cadmium, thallium, tin, lead, antimony, iron, nickel, cobalt, and palladium. Dry organic solvents were evaluated for the deposition of metals based on a study involving deposition of antimony from soltions of antimony (III) chloride. The use of organic liquids for the preparation of anhydrous metal halides is also presented. Reaction mechanisms for both organic liquids and aqueous system are discussed.
Philipp, W. H.↗
X-ray photoemission studies of superficially oxidized cesium antimonide photoemitters
Superficially oxidized cesium antimonide photoemitting surfaces prepared in ultrahigh vacuum were studied by X-ray photoelectron spectroscopy. Oxidation of Cs3Sb to produce a surface with enhanced photosensitivity converts part of the antimony to elemental antimony and part of the cesium to cesium suboxide. The latter is identified on the basis of an O1 s peak at 531.3 eV, characteristic of Cs11O3. The production of Cs2O is not ruled out in this process since its signature at 527.5 eV is masked by an antimony shake-up peak at 527 eV.
Bates, C. W., Jr.↗
Filter development for the extreme ultraviolet explorer
Thin film filters with extreme ultraviolet bandpasses unattainable with previously available filter materials were developed. Titanium and antimomy were identified as the most promising materials for providing the scientifically important 350-500 A bandpass heretofore unattainable with thin film filters. Titanium foils and titanium-antimony sandwich foils of the required uniformity and durability were fabricated. Transmission measurements and optimization studies indicate that the titanium-antimony combination provides an ideal bandpass for scientifically valuable, high-sensitivity observations with EUVE. Environmental testing of the mechanical strength, moisture sensitivity and aging characteristics of the newly developed filter materials demonstrate flightworthy performance.
Kimble, R.↗
Heat sealable, flame and abrasion resistant coated fabric
Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.
Tschirch, R. P.↗
Heat sealable, flame and abrasion resistant coated fabric
Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.
Tschirch, R. P.↗
El Chichon - Composition of plume gases and particles
Aircraft measurements were made of trace gases, atmospheric particles, and condensed acid volatiles in the plume of El Chichon volcano, Chiapas, Mexico, in November 1982. Hydrogen sulfide was the primary gaseous sulfur species in the plume at the time of collection. Concentrations of 28 elements were determined by neutron activation analysis of particulate material from the plume. The volatile elements sulfur, chlorine, arsenic, selenium, bromine, antimony, iodine, tungsten, and mercury were enriched relative to bulk pyroclastic material by factors of 60 to 20,000. Arsenic, antimony, and selenium were associated predominantly with small (not greater than 3 micrometer) particles. Calcium and sodium were present almost exclusively on larger particles and aluminum and manganese were bimodally distributed. Ashladen particulate material injected into the stratosphere during the early violent eruptions was enriched by factors of 10 to 30 relative to ash in some of the same elements observed in the quiescent plume.
Kotra, J. P.↗
The influence of Sb doping on the growth and electronic properties of GaAs(100) and AlGaAs(100)
Isoelectronic doping using antimony has been shown to reduce traps and improve material properties during epitaxial growth of Si doped GaAs(100) and AlGaAs(100). In this study, the effect of the antimony dopant on the optimal growth temperature is examined with the aim of producing high-quality heterostructures at lower temperatues. High-quality films of GaAs and AlGaAs have been grown by molecular-beam epitaxy at the normal growth temperatures of 610 and 700 C, respectively, and 50-100 C below this temperature using varying small amounts of Sb as a dopant. Electrical properties of the films were then examined using Hall mobility measurements and deep-level transient spectroscopy.
Jamison, K. D.↗
The development of infrared detectors and mechanisms for use in future infrared space missions
The environment above earth's atmosphere offers significant advantages in sensitivity and wavelength coverage in infrared astronomy over ground-based observatories. In support of future infrared space missions, technology development efforts were undertaken to develop detectors sensitive to radiation between 2.5 micron and 200 micron. Additionally, work was undertaken to develop mechanisms supporting the imaging and spectroscopy requirements of infrared space missions. Arsenic-doped-Silicon and Antimony-doped-Silicon Blocked Impurity Band detectors, responsive to radiation between 4 micron and 45 micron, were produced in 128x128 picture element arrays with the low noise, high sensitivity performance needed for space environments. Technology development continued on Gallium-doped-Germanium detectors (for use between 80 micron and 200 micron), but were hampered by contamination during manufacture. Antimony-doped-Indium detectors (for use between 2.5 micron and 5 micron) were developed in a 256x256 pixel format with high responsive quantum efficiency and low dark current. Work began on adapting an existing cryogenic mechanism design for space-based missions; then was redirected towards an all-fixed optical design to improve reliability and lower projected mission costs.
Houck, James R.↗
High Electron Mobility SiGe/Si Transistor Structures on Sapphire Substrates
SiGe/Si n-type modulation doped field effect structures and transistors (n-MODFETs) have been fabricated on r-plane sapphire substrates. The structures were deposited using molecular beam epitaxy, and antimony dopants were incorporated via a delta doping process. Secondary ion mass spectroscopy (SIMS) indicates that the peak antimony, concentration was approximately 4 x 10(exp19) per cubic cm. The electron mobility was over 1,200 and 13,000 sq cm/V-sec at room temperature and 0.25 K, respectively. At these two temperatures, the electron carrier densities were 1.6 and 1.33 x 10(exp 12) per sq cm, thus demonstrating that carrier confinement was excellent. Shubnikov-de Haas oscillations were observed at 0.25 K, thus confirming the two-dimensional nature of the carriers. Transistors, with gate lengths varying from 1 micron to 5 microns, were fabricated using these structures and dc characterization was performed at room temperature. The saturated drain current region extended over a wide source-to-drain voltage (V(sub DS)) range, with (V(sub DS)) knee voltages of approximately 0.5 V and increased leakage starting at voltages slightly higher than 4 V.
Alterovitz, Samuel A.↗
High Electron Mobility SiGe/Si Transistor Structures on Sapphire Substrates
SiGe/Si n-type modulation doped field effect structures and transistors (n-MODFETs) have been fabricated on r-plane sapphire substrates. The structures were deposited using molecular beam epitaxy, and antimony dopants were incorporated via a delta doping process. Secondary ion mass spectroscopy (SIMS) indicates that the peak antimony concentration was approximately 4 x 10(exp 19) per cubic centimeter. At these two temperatures, the electron carrier densities were 1.6 and 1.33 x 10(exp 12) per square centimeter, thus demonstrating that carrier confinement was excellent. Shubnikov-de Haas oscillations were observed at 0.25 K, thus confirming the two-dimensional nature of the carriers. Transistors, with gate lengths varying from 1 micron to 5 microns, were fabricated using these structures and dc characterization was performed at room temperature. The saturated drain current region extended over a wide source-to-drain voltage (V (sub DS)) range, with V (sub DS) knee voltages of approximately 0.5 V and increased leakage starting at voltages slightly higher than 4 V.
Alterovitz, Samuel A.↗
N-Type delta Doping of High-Purity Silicon Imaging Arrays
A process for n-type (electron-donor) delta doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays. Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac delta function (impulse function): the dopant is highly concentrated in a very thin layer. Preferably, the dopant is concentrated in one or at most two atomic layers in a crystal plane and, therefore, delta doping is also known as atomic-plane doping. The use of doping to enable detection of high-energy photons and low-energy particles was reported in several prior NASA Tech Briefs articles. As described in more detail in those articles, the main benefit afforded by delta doping of a back-illuminated silicon detector is to eliminate a "dead" layer at the back surface of the silicon wherein high-energy photons and low-energy particles are absorbed without detection. An additional benefit is that the delta-doped layer can serve as a back-side electrical contact. Delta doping of p-type silicon detectors is well established. The development of the present process addresses concerns specific to the delta doping of high-purity silicon detectors, which are typically n-type. The present process involves relatively low temperatures, is fully compatible with other processes used to fabricate the detectors, and does not entail interruption of those processes. Indeed, this process can be the last stage in the fabrication of an imaging detector that has, in all other respects, already been fully processed, including metallized. This process includes molecular-beam epitaxy (MBE) for deposition of three layers, including metallization. The success of the process depends on accurate temperature control, surface treatment, growth of high-quality crystalline silicon, and precise control of thicknesses of layers. MBE affords the necessary nanometer- scale control of the placement of atoms for delta doping. More specifically, the process consists of MBE deposition of a thin silicon buffer layer, the n-type delta doping layer, and a thin silicon cap layer. The n dopant selected for initial experiments was antimony, but other n dopants as (phosphorus or arsenic) could be used. All n-type dopants in silicon tend to surface-segregate during growth, leading to a broadened dopant-concentration- versus-depth profile. In order to keep the profile as narrow as possible, the substrate temperature is held below 300 C during deposition of the silicon cap layer onto the antimony delta layer. The deposition of silicon includes a silicon- surface-preparation step, involving H-termination, that enables the growth of high-quality crystalline silicon at the relatively low temperature with close to full electrical activation of donors in the surface layer.
Blacksberg, Jordana↗
Performance test results of a skutterudite-based unicouple with a metallic coating
A performance test of a Skutterudite-based unicouple (MAY-04) with a metallic coating to suppress the sublimation of antimony from the legs near the hot junction is performed in vacuum (~ 9 x10-7 torr) for ~ 2,000 hours at hot and cold junction temperatures of 892.1 + 11.9 K and 316.1 + 5.5 K, respectively. The p-leg is made of CeFe3.5Co0.5Sb12 and the n-leg is made of CoSb3. Presented are the measured voltage-current characteristics, electrical power, open-circuit voltage, and Seebeck coefficients of the legs as functions of cumulative test time. Also presented is the estimate of the conversion efficiency, shortly (~ 96 hrs) after the start of test. To demonstrate the effectiveness of the metallic coating, the measurements for MAY-04 are compared with those of two uncoated unicouples of the same leg materials (MAR-03 and JUN-03), which had been tested earlier. The cross-sectional areas of the legs in MAY-04 are larger than those in MAR-03 and JUN-03, tested in argon cover gas at ~ 0.051-0.068 MPa for 450 and 1200 hours, respectively. The open circuit voltage, Voc (204 mV) of MAY-04 at Beginning-Of-Test (BOT) is almost the same as that of MAR-03, but higher than that of JUN-03 (~180 mV). Although the argon gas effectively decreased antimony loss from legs of MAR-03 and JUN-03, marked degradations in performance occurred with time in these tests. Conversely, the metallic coating in MAY-04 effectively reduced the performance degradation with cumulative test time. The estimated peak efficiency of MAY-04, shortly after BOT (10.65%) is only ~ 0.37 percentage point lower than the theoretical value, assuming zero side heat losses and zero contact resistance per leg. The peak power of MAY- 04 decreased by only ~12%, from its BOT value of ~1.6 We to ~ 1.4 We after ~ 2,000 of cumulative testing
Caillat, Thierry↗
Un-Numbered Operational Areas PRL 229 Railroad Tie Disposal Area Pond Confirmation Sampling Report
This Confirmatory Sampling (CS) Report (CSR) was prepared for the National Aeronautics and Space Administration (NASA), Kennedy Space Center (KSC), Florida in accordance with the CS Work Plan (CSWP) (HGL, 2022a). The CSR summarizes investigation activities performed on the Railroad Tie Disposal Area (RTDA) of the Un-Numbered Operational Areas (UNOA), Potential Release Location (PRL) 229 located at KSC. HydroGeoLogic, Inc. (HGL) prepared this report under Contract Number 80KSC019D0012. The purpose of the CSR is to provide information to evaluate the level of potential contamination in surface water and sediment samples collected from the RTDA PRL 229 Pond and determine if contaminants pose unacceptable risks to ecological receptors. The CSR provides analytical data of 10 sets of surface water and sediment samples collected in 2021. Surface water samples were analyzed for volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), polynuclear aromatic hydrocarbon (PAHs), metals, hardness, and salinity, while sediment samples were analyzed for metals, total organic carbon (TOC), SVOCs, PAHs, and total petroleum hydrocarbons (TPH). The CSR includes a Screening Level Ecological Risk Assessment (SLERA) conducted under KSC’s Resource Conservation and Recovery Act (RCRA) Corrective Action Program to determine if unacceptable risks to ecological receptors exist at PRL 229 Pond. Metals and PAHs were detected in surface water samples, including detections of antimony, arsenic, barium, calcium, copper, lead, magnesium, thallium, zinc, anthracene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeno(1,2,3-c,d)pyrene and pyrene. Based on measured salinity (1.03 to 1.21 parts per thousand), the pond was identified as freshwater. Sediment analytical results also contained detections of metals and PAHs, including antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, thallium, zinc, anthracene benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeno(1,2,3-c,d)pyrene and pyrene. Potential risks to ecological receptors were evaluated in accordance with the SLERA Work Plan and the Decision Process Document for the Resource Conservation and Recovery Act (RCRA) Corrective Action Program at KSC (DPD) (Geosyntec, 2019), and using the 2021 sediment and surface water analytical results. Potential ecological receptors evaluated in the SLERA include the aquatic community, benthic invertebrates, aquatic birds, and aquatic mammals. The SLERA included Steps 2a through 2c of the Ecological Risk Assessment (ERA) process in accordance with the DPD. Using multiple lines of evidence, the SLERA concluded that many of the detected analytes are present at concentrations similar to those in background or reference locations at KSC, and/or at concentrations that would not pose a significant risk to ecological communities. There are no screening values available for the avian community, and PAHs are bioaccumulative compounds. For this reason, food web modeling was completed as a supplement to Step 2c to provide a quantitative evaluation of this exposure pathway. Food web modeling indicates that PAHs are unlikely to pose a risk to birds exposed to site sediment and surface water. Based on the results of the SLERA, the contaminants in sediment and surface water pose no to minimal risk to the ecological communities that could live or forage at the site. Based on the results of the SLERA, no further study is recommended for the RTDA Pond at PRL 229.
Confirmation Sampling↗
Beta-gamma directional correlation in Sb super 125.
Directional correlation of first forbidden beta group and gamma ray in decay of antimony at four beta energies
FORBIDDEN BAND↗