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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Five new ternary indium-arsenides discovered. Synthesis and structural characterization of the Zintl phases Sr 3 In 2 As 4 , Ba 3 In 2 As 4 , Eu 3 In 2 As 4 , Sr 5 In 2 As 6 and Eu 5 In 2 As 6

Five new ternary indium aresenides, AE 3 In 2 As 4 ( AE =Sr, Ba, Eu), and AE 5 In 2 As 6 ( AE =Sr, Eu), have been synthesized using molten metal In, Pb, and Sn fluxes. Structure elucidation was aided by powder X-ray and single crystal X-ray diffraction. This demonstrated Sr 3 In 2 As 4 and Eu 3 In 2 As 4 are orthorhombic and isostructural to Sr 3 In 2 P 4 (space group Pnnm , Z =2), while Ba 3 In 2 As 4 is monoclinic and isostructural to Ca 3 Al 2 As 4 (space group C 2/ c , Z =4). In addition, Sr 5 In 2 As 6 and Eu 5 In 2 As 6 crystallize orthorhombically and adopt the Ca 5 Ga 2 As 6 structure type (space group Pbam , Z =2). The valence electron count for all structures conform to the Zintl-Klemm concept, and as such can be rationalized as divalent Sr, Ba, Eu cations and polyanionic In–As fragments of different dimensionality. In Sr 3 In 2 As 4 and Eu 3 In 2 As 4 , one-dimensional chains [In 2 As 4 ] 6– running along the crystallographic c -axis exist, and they are made up of edge- and corner-shared tetrahedra InAs 4 . The [In 2 As 4 ] 6– two-dimensional sheets in the structure of Ba 3 In 2 As 4 are composed of a pair of edge-shared InAs 4 tetrahedra, that are further connected by corner-sharing. In Sr 5 In 2 As 6 and Eu 5 In 2 As 6 , the InAs 4 tetrahedra are only corner-shared to make infinite [InAs 2 As 2/2 ] 6– chains running along the a -axis, which are dimerized via As–As bonds into [In 2 As 6 ] 10- ribbons. Furthermore, electronic structure calculations affirm these assignments and suggest intrinsic, narrow-gap seminconducting behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Mechanism and Features of Field Emission in Semiconductors

The field electron emission from individual grains on the surface of Si and III–V semiconductors, namely, gallium arsenide, indium arsenide, and indium antimonide is investigated by scanning tunneling microscopy. From the correspondence of the functional dependence of the I–V characteristic to the theory, the emission mechanism is determined as direct tunneling through a depleted or enriched subsurface layer at the voltages V < 1 V and the tunneling emission from the surface electronic states at the voltages V > 1 V. A field-emission threshold of (1–5) × 10{sup 6} V/cm is obtained, which is significantly lower than the values for metals and carbon. The determining factors of this emission mechanism are the Schottky effect, the localization and size quantization of “light” electrons in the surface area of III–V semiconductors, and the presence of a subsurface depletion layer in silicon. According to the data obtained for the values of the field-emission threshold, indium antimonide in the form of submicron grain particles is the most efficient field emitter.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Mechanisms of Current Transfer in Electrodeposited Layers of Submicron Semiconductor Particles

Current–voltage (I–V) characteristics of conductance in multigrain layers of submicron particles of silicon, gallium arsenide, indium arsenide, and indium antimonide have been studied. Nanoparticles of all semiconductors were obtained by processing initial single crystals in a ball mill and applied after sedimentation onto substrates by means of electrodeposition. Detailed analysis of the I–V curves of electrodeposited layers shows that their behavior is determined by the mechanism of intergranular tunneling emission from near-surface electron states of submicron particles. Parameters of this emission process have been determined. The proposed multigrain semiconductor structures can be used in gas sensors, optical detectors, IR imagers, etc.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Evaluation of silicon and indium gallium arsenide photodiodes as direct timing detectors for pulsed x-ray systems

Benchtop pulsed x-ray systems are commonly used to record dynamic material data on the order of nanoseconds, but pulse timing is often difficult to accurately determine. This study demonstrates that commercially available photodiodes can be used effectively for direct x-ray pulse detection without the need for visible light scintillators. X-ray pulses from four commercially available flash x-ray systems were quantified using one silicon and two indium gallium arsenide (InGaAs) photodiodes. The measured InGaAs pulse durations were strongly dependent on radiation dose in the non-linear operating regime, so the photodiodes were shielded to operate below the 2.5 V non-linear regime threshold. The average pulse duration and pulse arrival time jitter of the photodiodes for each x-ray source were within several nanoseconds with the exception of two sets of measurements that were affected by low instrument sensitivity and electrical noise. These results show that InGaAs photodiodes can be used as effective and repeatable stand-alone timing diagnostics for x-ray pulses as short as 20 ns or less.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Indium Arsenide-Based Spontaneous Emission Sources (Review: a Decade Later)

The results of investigations of light-emitting diodes based on heterostructures with an InAs active region grown by liquid phase and metalorganic vapor-phase epitaxy over the last decade are reviewed. The near-field pattern, L–I and I–V characteristics, and quantum efficiency of point-contact and flip-chip light-emitting diodes are analyzed in a wide temperature range.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Superlattice photodetector having improved carrier mobility

In a superlattice (SL) photodetector, each period of the SL includes first and second semiconductor layers having different compositions, at least one of which comprises indium arsenide (InAs). At least one of these two semiconductor layers has a graded composition. In embodiments, the first semiconductor layer comprises InAs and the second semiconductor layer is a graded layer comprising indium arsenide antimonide (InAsSb), wherein the antimony (Sb) concentration is varied. In examples, the Sb concentration in the second layer gradually increases from the top and bottom toward the middle of the layer.

Kim, Jin K.↗
DOE OSTI2018

Single Nanocrystal Spectroscopy of Shortwave Infrared Emitters

Short-wave infrared (SWIR) emitters are at the center of ground-breaking applications in biomedical imaging, next-generation optoelectronic devices, and optical communications. Colloidal nanocrystals based on indium arsenide are some of the most promising SWIR emitters to date. However, the lack of single-particle spectroscopic methods accessible in the SWIR has prevented advances in both nanocrystal synthesis and fundamental characterization of emitters. In this paper, we demonstrate an implementation of a solution photon correlation Fourier spectroscopy (s-PCFS) experiment utilizing the SWIR sensitivity and time resolution of superconducting nanowire single-photon detectors to extract single-particle emission linewidths from colloidal indium arsenide/cadmium selenide (InAs/CdSe) core/shell nanocrystals emissive from 1.2 to 1.6 μm. We show that the average single InAs/CdSe nanocrystal fluorescence linewidth is, remarkably, as narrow as 52 meV, similar to what has been observed in some of the most narrowband nanostructured emitters in the visible region. Additionally, the single nanocrystal fluorescence linewidth increases with increasing shell thickness, suggesting exciton–phonon coupling as the dominant emission line-broadening mechanism in this system. The development of the SWIR s-PCFS technique has enabled measurements of spectral linewidths of colloidal SWIR-emissive NCs in solution and provides a platform to study the single NC spectral characteristics of SWIR emitters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Induced Superconducting Pairing in Integer Quantum Hall Edge States

Indium arsenide (InAs) near surface quantum wells (QWs) are promising for the fabrication of semiconductor–superconductor heterostructures given that they allow for a strong hybridization between the two-dimensional states in the quantum well and the ones in the superconductor. In this work, we present results for InAs QWs in the quantum Hall regime placed in proximity of superconducting NbTiN. We observe a negative downstream resistance with a corresponding reduction of Hall (upstream) resistance, consistent with a very high Andreev conversion. Further, we analyze the experimental data using the Landauer-Büttiker formalism, generalized to allow for Andreev reflection processes. We attribute the high efficiency of Andreev conversion in our devices to the large transparency of the InAs/NbTiN interface and the consequent strong hybridization of the QH edge modes with the states in the superconductor.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Carrier-Envelope Phase Control in Terahertz Pulse Generation Using InAs Ribbon Metasurfaces

Generation of broadband terahertz (THz) pulses with variable polarization and carrier-envelope phase can enable the tailoring of THz beam wavefronts for advanced applications in THz imaging and spectroscopy and for strong THz field optics. While metasurfaces composed of deeply subwavelength THz emitters have recently been demonstrated to define the polarization and spatial profile of the generated THz fields, precise phase control or synthesis of THz pulse waveforms remains a challenging problem. Here, we propose and demonstrate metasurfaces composed of indium arsenide (InAs) nanoscale ribbon arrays capable of generating THz pulses with variable carrier-envelope phase. We show that different THz generation mechanisms, each contributing distinct phases, can be activated in the ribbons, enabling carrier-envelope phase control spanning a range of π over a wide band of frequencies (∼1–3 THz). This is achieved solely through the ribbon array geometry using linearly polarized optical excitation of the ribbons. The arrays enable precise control of the THz phase and amplitude, opening the door to advanced structured THz wavefront synthesis using ultrathin dielectric metasurfaces.

carrier-envelope phase↗
DOE OSTI2017

On the high characteristic temperature of an InAs/GaAs/InGaAsP QD laser with an emission wavelength of ~1.5 μm on an InP substrate

We report on a study of lasers with an emission wavelength of about 1.5 μm and high temperature stability, synthesized on an InP (001) substrate. Self-organized InAs quantum dots capped with a thin GaAs layer are used as the active region of the laser. A quaternary InGaAsP solid solution with a band-gap width of 1.15 eV serves as the waveguide/matrix layer. A high characteristic temperature of the threshold current, T{sub 0} = 205 K, is reached in the temperature range 20–50°C in ridge-waveguide laser diodes. A correlation between the values of T{sub 0} and the band-gap width of the waveguide layers is found.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Molecular-beam epitaxy of InGaAs/InAlAs/AlAs structures for heterobarrier varactors

The molecular-beam epitaxy of InGaAs/InAlAs/AlAs structures for heterobarrier varactors is studied and optimized. The choice of the substrate-holder temperature, growth rate and III/V ratio in the synthesis of individual heterostructure regions, the thickness of AlAs inserts and barrier-layer quality are critical parameters to achieve the optimal characteristics of heterobarrier varactors. The proposed triple-barrier structures of heterobarrier varactors with thin InGaAs strained layers immediately adjacent to an InAlAs/AlAs/InAlAs heterobarrier, mismatched with respect to the InP lattice constant at an AlAs insert thickness of 2.5 nm, provides a leakage current density at the level of the best values for heterobarrier varactor structures with 12 barriers and an insert thickness of 3 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Cleaved-edge photoluminescence spectroscopy of multilayer heterostructures

The capabilities of a technique based on combined photoluminescence and Raman-spectroscopy measurements upon lateral scanning across the cleaved edge of heterostructures for monitoring the strain profile and the thickness of epitaxial layers are demonstrated. The characteristics of a laser heterostructure with InGaAs/GaAsP quantum wells are investigated by this technique. It is shown that photoluminescence from different layers of the structure can be recorded separately. It is established that both the frequency of the InP-like phonon mode and the photoluminescence energy can be used to determine the composition of the In{sub x}Ga{sub 1–x}P alloy. The two methods yield close results.

36 MATERIALS SCIENCE↗
DOE OSTI2018

On the Impact of Barrier-Layer Doping on the Photoluminescence Efficiency of InGaAlAs/InGaAs/InP Strained-Layer Heterostructures

The photoluminescence of strained InGaAlAs/InGaAs/InP heterostructures with an active region consisting of nine In{sub 0.74}Ga{sub 0.26}As quantum wells and δ-doped In{sub 0.53}Al{sub 0.20}Ga{sub 0.27}As barrier layers grown by molecular beam epitaxy on an InP(100) substrate is investigated. Analysis of the photoluminescence spectra demonstrates that p-type doping leads to an increase in the photoluminescence efficiency at low excitation levels in comparison to a heterostructure with undoped barriers, and increasing the level of barrier doping to (1–2) × 10{sup 12} cm{sup –2} results in the suppression of nonradiative recombination.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Search for Asymmetric Barrier Layers for 1550 nm Al-Free Diode Lasers

A search for materials suitable for implementation of 1.55 µm Al-free diode lasers based on InP with asymmetric barrier (AB) layers is conducted. It is shown that a very high (over 10{sup 6}) suppression ratio of the parasitic electron flux can be achieved using common III–V alloys for the ABs. Hence placing such ABs in the immediate vicinity of the active region should completely suppress the parasitic recombination in the waveguide. Several optimal AB designs are proposed that are based on one of the following alloys: Al-free GaInPSb, ternary AlInAs, or quaternary AlGaInAs with a low Al-content. As an important and beneficial byproduct of utilization of such ABs, an improvement of majority carrier capture into the active region occurs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Spontaneous Emission and Lasing of a Two-Wavelength Quantum-Cascade Laser

The results of experiments on the fabrication (by molecular-beam epitaxy) and investigation of the heterostructures of a two-frequency quantum-cascade laser produced on the basis of a heteropair of In{sub 0.53}Ga{sub 0.47}As/Al{sub 0.48}In{sub 0.52}As solid solutions on an InP substrate are presented. The heterostructures contained quantum cascades emitting at a wavelength of 9.6 μm and cascades emitting at a wavelength of 7.6 μm. The high structural quality of the fabricated heterostructures is shown. The spontaneous emission and lasing spectra are investigated and the multimodal laser generation of stripe lasers at a wavelength of 7.6 μm is demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗