Showing papers on "Antimonide published in 2010"

Antimonide-based barrier infrared detectors

Abstract: The nearly lattice-matched InAs/GaSb/AlSb (antimonide) material system offers tremendous flexibility in realizing high-performance infrared detectors. Antimonide-based alloy and superlattice infrared absorbers can be customized to have cutoff wavelengths ranging from the short wave infrared (SWIR) to the very long wave infrared (VLWIR). They can be used in constructing sophisticated heterostructures to enable advanced infrared photodetector designs. In particular, they facilitate the construction of unipolar barriers, which can block one carrier type but allow the unimpeded flow of the other. Unipolar barriers are used to implement the barrier infra-red detector (BIRD) design for increasing the collection efficiency of photo-generated carriers, and reducing dark current generation without impeding photocurrent flow. We report our recent efforts in achieving state-of-the-art performance in antimonide alloy and superlattice based infrared photodetectors using the BIRD architecture. Specifically, we report a 10 μm cutoff superlattice device based on a complementary barrier infrared detector (CBIRD) design. The detector, without antireflection coating or passivation, exhibits a responsivity of 1.5 A/W and a dark current density of 1×10-5 A/cm2 at 77K under 0.2 V bias. It reaches 300 K background limited infrared photodetection (BLIP) operation at 87 K, with a blackbody BLIP D* value of 1.1×1011 cm-Hz1/2/W for f/2 optics under 0.2 V bias.

Technologies for thermal management of mid-IR Sb-based surface emitting lasers

Abstract: In this paper, for the first time to our knowledge, we report and demonstrate the technological steps dedicated to thermal management of antimonide-based surface emitting laser devices grown by molecular beam epitaxy. Key points of the technological process are firstly the bonding of the structure on the SiC host substrate and secondly the GaSb substrate removal to leave the Sb-based membrane. The structure design (etch stop layer, metallic mirror, etc), bonding process (metallic bonding via solid–liquid interdiffusion) and GaSb substrate removal process (selective wet-chemical etchants, etc) are presented. Optical characterizations together with external-cavity VCSEL laser emission at 2.3 µm at room temperature in continuous wave are presented.

Nanosize Transition Metal Antimonides, NiSb and FeSb2: Solvothermal Synthesis and Characterization

Abstract: Transition metal antimonide nanoparticles, NiSb and FeSb2, were synthesized by solvothermal method with the inclusion of various kinds of additives. X-ray diffraction (XRD) analysis confirmed the formation of hexagonal NiSb and orthorhombic FeSb2. NiSb nanoparticles of diameter about 10-40 nm and FeSb2 nanorods of 6 nm wide and 15-30 nm long were synthesized with the addition of SDS as surfactant. The structural analysis by transmission electron microscopy (TEM) also revealed the formation of transition metal antimonide nanoparticles with high purity and better crystallinity. The effect of the nanostructure on the UV-vis absorption and luminescence of the antimonide nanoparticles has been studied. The nanosize transition metal antimonides such as NiSb and FeSb2 have applications as inclusion materials in CoSb3 skutterudites in developing thermoelectric devices with better energy conversion efficiency.

Self-nucleation and growth of group III-antimonide nanowires

Abstract: In this paper, we show that the growth of III-antimonides can occur via self-catalysis using either group III metal or Sb clusters at their tips. Specific experiments using GaSb and InSb systems show that bulk nucleation and growth of the respective antimonide wires can also occur from mm-sized droplets. The role of equilibrium solubility and the size of the droplet on bulk nucleation versus tip-led growth is discussed.

Optical performances of InAs/GaSb/InSb short-period superlattice laser diode for mid-infrared emission

Abstract: An antimonide-based InAs/GaSb/InSb short-period superlattice (SPSL) laser diode on GaSb substrate for mid-infrared emission has been modeled by an accurate eight-band k.p model. By using a realistic graded and asymmetric interface profile, calculated energy gap between the electron and heavy-hole miniband shows good agreement with our experimental data. Optical gain and threshold current density are then presented and compared with experimental results of SPSL laser diodes operating in pulsed regime. Analysis of the optical performances obtained at room temperature is made.

Synthesis, Crystal and Electronic Structures of New Narrow-Band-Gap Semiconducting Antimonide Oxides RE3SbO3 and RE8Sb3−δO8, with RE = La, Sm, Gd, and Ho

Abstract: In the search for high-temperature thermoelectric materials, two families of novel, narrow-band-gap semiconducting antimonide oxides with the compositions RE3SbO3 and RE8Sb3−δO8 (RE = La, Sm, Gd, Ho) have been discovered. Their synthesis was motivated by attempts to open a band gap in the semimetallic RESb binaries through a chemical fusion of RESb and corresponding insulating RE2O3. Temperatures of 1350 °C or higher are required to obtain these phases. Both RE3SbO3 and RE8Sb3−δO8 adopt new monoclinic structures with the C2/m space group and feature similar REO frameworks composed of “RE4O” tetrahedral units. In both structures, the Sb atoms occupy the empty channels within the REO sublattice. High-purity bulk Sm and Ho samples were prepared and subjected to electrical resistivity measurements. Both the RE3SbO3 and RE8Sb3−δO8 (RE = Sm, Ho) phases exhibit a semiconductor-type electrical behavior. While a small band gap in RE3SbO3 results from the separation of the valence and conduction bands, a band gap i...

Advanced composite high-κ gate stack for mixed anion arsenide-antimonide quantum well transistors

Abstract: This paper demonstrates the integration of a composite high-κ gate stack (3.3 nm Al 2 O 3 −1.0 nm GaSb) with a mixed anion InAs 0.8 Sb 0.2 quantum-well field effect transistor (QWFET). The composite gate stack achieves; (i) EOT of 4.2 nm with <10−7A/cm2 gate leakage (ii) low D it interface (∼1×1012 /cm2/eV) (iii) high drift µ of 3,900–5,060 cm2/V-s at N S of 5×1011−3×1012/cm2. The InAs 0.8 Sb 0.2 MOS-QWFETs with composite gate stack exhibit extrinsic (intrinsic) g m of 334 (502) µS/µm and drive current of 380 µA/µm at V DS = 0.5V for Lg=1µm.

Molecular beam epitaxial growth effects on type-II antimonide lasers and photodiodes

Abstract: Two important classes of electro-optical devices, midwave-infrared interband cascade lasers (ICLs) and long-wave infrared photodiodes, employ type-II antimonide active regions grown by molecular beam epitaxy (MBE). The authors have studied how growth temperature and As flux affect the integrated intensity and linewidth of low-temperature photoluminescence spectra emitted from ICL active regions. Possible ramifications for defect-assisted Auger processes are discussed, and experimental Auger coefficients are extracted from the measured ICL thresholds and slope efficiencies. They also demonstrate that the effective dynamic impedance of a type-II photodiode with graded-gap depletion region is quite sensitive to the doping level in the absorber. Majority acceptor concentration is a key design parameter that must be carefully controlled in the MBE growth.

Optical Studies on Antimonide Superlattice Infrared Detector Material

Abstract: In this study the material quality and optical properties of type II InAs/GaSb superlattices are investigated using transmission and photoluminescence (PL) spectroscopy. The influence of the material quality on the intensity of the luminescence and on the electrical properties of the detectors is studied and a good correlation between the photodetector current-voltage (IV) characteristics and the PL intensity is observed. Studies of the temperature dependence of the PL reveal that Shockley-Read-Hall processes are limiting the minority carrier lifetime in both the mid-IR wavelength and the long-IR wavelength detector material studied. These results demonstrate that PL spectroscopy is a valuable tool for optimization of infrared detectors.

Fermi level unpinning of GaSb(100) using Plasma Enhanced ALD Al 2 O 3 dielectric

Abstract: Antimonide based compound semiconductors have gained considerable interest in recent years due to their superior electron and hole transport properties [1–3]. Among the various high mobility material systems (Fig. 1), arsenic-antimonide based MOS-HEMTs have great potential to enable complementary logic operation at low supply voltage. Integrating a high quality dielectric is key to demonstrating a scalable arsenic-antimonide MOS-HEMT architecture for 15 nm logic technology node and beyond. It is hypothesized that an ultra-thin GaSb surface layer is more favorable toward high-к integration than In 0.2 Al 0.8 Sb barrier as it avoids Al at the interface and the associated surface oxidation. Here, we study the effects of various surface passivation approaches on the capacitance-voltage characteristics (C-V) and the surface chemistry of n-type and p-type GaSb(100) MOS capacitors made with ALD and Plasma Enhanced ALD (PEALD) Al 2 O 3 dielectric. We demonstrate for the first time, unpinned Fermi level in GaSb MOS system with high-к PEALD Al 2 O 3 dielectric using admittance spectroscopy and XPS analysis.

Theory-guided growth of aluminum antimonide single crystals with optimal properties for radiation detection

Abstract: First-principles calculations are used to study the thermodynamic and electronic properties of a large set of intrinsic and extrinsic defects in AlSb The results are employed in conjunction with experimental impurity data to devise an improved growth process for mitigating the detrimental effects of native defects and impurities A codoping strategy using Te is demonstrated that leads to a significant increase in both mobility and resistivity without introducing lifetime-limiting deep levels The resulting material exhibits an order of magnitude improvement in mobility-lifetime product and allows spectroscopic detection of α particles with AlSb

Growth and performance of superlattice-based long wavelength complementary barrier infrared detectors (CBIRDs)

Abstract: We have demonstrated the use of bulk antimonide based materials and type-II antimonide based superlattices in the development large area long wavelength infrared (LWIR) focal plane arrays (FPAs) Barrier infrared photodetectors (BIRDS) and superlattice-based infrared photodetectors are expected to outperform traditional III-V MWIR and LWIR imaging technologies and are expected to offer significant advantages over II-VI material based FPAs Our group has developed a novel complementary barrier infrared detector (CBIRD) which utilizes properties unique to the antimonide material system to incorporate unipolar barriers on either side of a superlattice absorber region We have used molecular beam epitaxy (MBE) technology to grow InAs/GaSb CBIRD structures on large area 100mm GaSb substrates with excellent results Furthermore, we have fabricated initial 1024x1024 pixels superlattice imaging FPAs based on the CBIRD concept

High-operating-temperature MWIR photon detectors based on type II InAs/GaSb superlattice

Abstract: Recent efforts have been paid to elevate the operating temperature of Type II InAs/GaSb superlattice Mid Infrared photon detectors. Optimized growth parameters and interface engineering technique enable high quality material with a quantum efficiency above 50%. Intensive study on device architecture and doping profile has resulted in almost one order of magnitude of improvement to the electrical performance and lifted up the 300K-background BLIP operation temperature to 166K. At 77K, the ~4.2 m cut-off devices exhibit a differential reP sistance area product in excess of the measurement system limit (10 6 Ohm.cm 2 ) and a detectivity of 3x10 13 cm.Hz 1/2 /W. High quality focal plane arrays were demonstrated with a noise equivalent temperature of 10mK at 77K. Uncooled camera is capable to capture hot objects such as soldering iron. Keywords: Type II superlattice, InAs/GaS b, M-structure, photodetector s, MWIR, focal plane arrays. INTRODUCTION: TYPE II ANTIMONIDE BASED SUPERLATTICES

A preparation method for antimonide molybdenum base thermoelectric material

Abstract: The invention relates to a doping molybdenum antimonide-based thermoelectric material and the preparation method, which is characterized in that the invention adopts arc melting and discharging plasma rapid sintering method for combination. The preparation method which is provided by the invention is the arc melting and the discharging plasma rapid sintering; Sb and Te/Se are firstly melted to form Sb2Te3Sb2Se3 and then are treated with the arc melting with the stoichiometric ratio of Mo and Sb; finally, the discharging plasma rapid sintering technology is introduced for preparing a dense single-phase material. The invention provides the rapid, simple and effective preparation method of the molybdenum antimonide-based thermoelectric material, which has good practical prospect.

Synthesis, Crystal and Electronic Structures, and Physical Properties of Caged Ternary Cu-Rich Antimonide: BaCu7.31(3)Sb5

Abstract: A new caged Cu-rich antimonide, BaCu7.31(3)Sb5, was obtained from a direct combination of the elements in a graphite crucible under a high vacuum by a solid state reaction, and the structure was determined by the single-crystal X-ray diffraction method to be hexagonal P63/mmc (No.194), with a = 7.0154(4) A, c = 12.5423(14) A, V = 534.58(7) A3, and Z = 2. BaCu7.31(3)Sb5 is the first antimonide member of the BaNi9P5-type barium copper pnictides with a Cu2 site occupancy of 43.7(9)%, and the structure building unit is a 30-vertex Cu18Sb12 cage centered by a Ba atom. The Cu18Sb12 cages form chains along the c axis by sharing the opposite hexagonal (Cu2)3(Sb2)3 faces. Such a cage chain shares (Cu1)2(Sb1)2 rhomboidal faces with six neighboring chains along the [100], [010], and [110] directions to generate a 3D condensed metallic network. The electronic structure calculations by CASTEP indicate the metallic nature, which matches well with the metallic electrical conductivity, small Seebeck coefficient, and Paul...

Epitaxial growth design and method for realizing high-efficiency 1.5mu m communication band laser structure by adopting cylindrical InGaSb quantum dots

Abstract: With specific lattice parameters and energy band structure properties, III-V antimonides show more and more important research value and application value in the aspect of near and medium infrared semiconductor devices. The research and development of GaAs-based 1.5mu m Sb-based quantum dot lasers can provide the probability for replacing InP-based material devices, overcome the disadvantages of difficult superintegration among the InP-based materials and poor temperature stability, and provide a novel optical source with low cost, low power consumption and good performance for optical communication. The invention relates to epitaxial growth design and a method for realizing high-efficiency 1.5mu m communication band laser structure by adopting cylindrical InGaSb quantum dots, which can realize the research and development of the low-dimension epitaxial growth of antimonide systems.

Growth and Characterization of Antimony-Based Narrow-Bandgap III-V Semiconductor Crystals for Infrared Detector Applications

Abstract: Materials for the generation and detection of 7–12 μm wavelength radiation continue to be of considerable interest for many applications such as night vision, medical imaging, sensitive pollution gas monitoring, etc. For such applications HgCdTe has been the main material of choice in the past. However, HgCdTe lacks stability and uniformity over a large area, and only works under cryogenic conditions. Because of these problems, antimony-based III–V materials have been considered as alternatives. Consequently, there has been a tremendous growth in research activity on InSb-based systems. In fact, InSb-based compounds have proved to be interesting materials for both basic and applied research. This chapter presents a comprehensive account of research carried out so far. It explores the materials aspects of indium antimonide (InSb), indium bismuth antimonide (InBi x Sb1–x), indium arsenic antimonide (InAs x Sb1–x), and indium bismuth arsenic antimonide (InBi x As y Sb1–x–y) in terms of crystal growth in bulk and epitaxial forms and interesting device feasibility. The limiting single-phase composition of InAs x Sb1–x and InBi x Sb1–x using near-equilibrium technique has been also addressed. An overview of the structural, transport, optical, and device-related properties is presented. Some of the current areas of research and development have been critically reviewed and their significance for both understanding the basic physics as well as device applications are discussed. These include the role of defects and impurity on structural, optical, and electrical properties of the materials.

Antimonide based infrared materials: Developments in InSb and GaSb substrate technologies

Abstract: In this work we report on the crystal growth and surface characterization of antimonide substrate materials. The Czochralski technique has been used to grow single crystal InSb and GaSb ingots with typical etch pit densities of <1E2 cm−2 and <2E3 cm−2, respectively. X-Ray topographs (XRT) have enabled the high resolution mapping of the defect structure in GaSb substrates, demonstrating that ingots can be produced with large areas of zero dislocation density. Epitaxyready surfaces with very low levels of surface roughness and uniform oxide coverage have been demonstrated for 4” GaSb. We have shown that smaller diameter antimonide ingot and wafer production processes can be scaled to deliver high quality substrates in large diameter form.

Polarized-neutron-scattering study of the spin-wave excitations in the 3-k ordered phase of uranium antimonide.

Abstract: The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.

Crystal Structure and Physical Properties of the New Antimonide Hf3Cu2Ge3.58Sb1.42

Abstract: The antimonide Hf3Cu2Ge3.58Sb1.42 was obtained via a two-step synthesis: arc-melting of hafnium, copper, and germanium under argon was followed by a reaction of the thus obtained ingot with antimon...

Room temperature aluminum antimonide radiation detector and methods thereof

Abstract: In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25° C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

Minority electron unipolar photodetectors based on type II InAs/GaSb/AlSb superlattices for very long wavelength infrared detection

Abstract: The bandstructure tunability of Type II antimonide-based superlattices has been significantly enhanced since the introduction of the M-structure superlattice, resulting in significant improvements of Type II superlattice infrared detectors. By using M-structure, we developed the pMp design, a novel infrared photodetector architecture that inherits the advantages of traditional photoconductive and photovoltaic devices. This minority electron unipolar device consists of an M-structure barrier layer blocking the transport of majority holes in a p-type semiconductor, resulting in an electrical transport due to minority carriers with low current density. Applied for the very long wavelength detection, at 77K, a 14μm cutoff detector exhibits a dark current 3.3 mA/cm2, a photoresponsivity of 1.4 A/W at 50mV bias and the associated shot-noise detectivity of 4x1010 Jones.

Synthesis, Structure and Properties of Scandium Dysprosium Antimonide, ScDySb

Abstract: Scandium dysprosium antimonide ScDySb was synthesized from scandium metal and DySb in an all-solid state reaction at 1770 K. According to X-ray analysis of the crystal structure [P4/nmm, Z = 4, a = 430.78(1) pm, c = 816.43(4) pm, R1 = 0.0238, wR(all) = 0.0688, 268 independent reflections], ScDySb adopts the anti-PbFCl type of structure, but with pronounced deviations in structural details, which are related to specific bonding interactions between the atoms involved. ScDySb shows antiferromagnetic ordering below 35.4 K, which was verified by susceptibility, heat capacity, and resistivity measurements. X-ray structure determination, performed at 30 K, showed no significant structural changes to occur during the magnetic phase transition. The band structure was calculated in the framework of Density Functional Theory. The bonding properties are comparable to those of Sc2Sb. Pronounced basins of the Electron Localization Function (ELF) appear in the tetragonal pyramidal Sc4Dy voids.