Showing papers on "Antimonide published in 2015"

Room temperature GaAsSb single nanowire infrared photodetectors.

Abstract: Antimonide-based ternary III-V nanowires (NWs) allow for a tunable bandgap over a wide range, which is highly interesting for optoelectronics applications, and in particular for infrared photodetection. Here we demonstrate room temperature operation of GaAs0.56Sb0.44 NW infrared photodetectors grown by metal organic vapor phase epitaxy. These GaAs0.56Sb0.44 NWs have uniform axial composition and show p-type conductivity with a peak field-effect mobility of ∼12 cm(2) V(-1) s(-1)). Under light illumination, single GaAs0.56Sb0.44 NW photodetectors exhibited typical photoconductor behavior with an increased photocurrent observed with the increase of temperature owing to thermal activation of carrier trap states. A broadband infrared photoresponse with a long wavelength cutoff at ∼1.66 μm was obtained at room temperature. At a low operating bias voltage of 0.15 V a responsivity of 2.37 (1.44) A/W with corresponding detectivity of 1.08 × 10(9) (6.55 × 10(8)) cm√Hz/W were achieved at the wavelength of 1.3 (1.55) μm, indicating that ternary GaAs0.56Sb0.44 NWs are promising photodetector candidates for small footprint integrated optical telecommunication systems.

Sensitive detection of carbon monoxide based on a QEPAS sensor with a 2.3 μm fiber-coupled antimonide diode laser

Abstract: In this paper, a sensitive quartz-enhanced photoacoustic spectroscopy (QEPAS)–based carbon monoxide (CO) sensor using a 23 μm continuous wave (CW) distributed feedback (DFB) fiber-coupled antimonide diode laser is demonstrated for the first time Wavelength modulation spectroscopy and a second-harmonic detection technique are used to reduce the sensor background noise and simplify the data process Water vapor is added into a 1000 ppm CO:N2 gas mixture to improve the vibrational–translational relaxation rate of the analyzed CO for the purpose of enhancement of the QEPAS signal After the modulation depth is optimized, a minimum detection limit of 433 ppm at the 42946 cm−1 absorption line is achieved when the modulation depth is set to 032 cm−1

First-principle study on lithium intercalated antimonides Ag3Sb and Mg3Sb2

Abstract: First-principle calculations based on density functional theory have been performed to investigate the negative electrode behaviors, structural changes, and electronic and bonding properties of lithium intercalated antimonides Ag3Sb and Mg3Sb2. Initial intercalation of lithium to orthorhombic Ag3Sb led to form cubic Li2AgSb. Lithium insertion to hexagonal Mg3Sb2 results in cubic LiMgSb. Further insertion of lithium with the intercalated compounds Li2AgSb and LiMgSb results in to the formation of alkali antimonide Li3Sb. The structural transformation of both antimonides Ag3Sb and Mg3Sb2 followed by the insertion of Li+ ends with the formation of Li3Sb with cubic phase. The computed band structures along high symmetry directions of the Brillouin zone, and total and partial density of states clearly illustrate that the intercalation of lithium with Ag3Sb and Mg3Sb2 changes their metallic nature into semiconductor. From the charge density calculations, it is observed that the covalent bond nature in the parent phases Ag3Sb and Mg3Sb2 changed into ionic bond in the Li+ intercalated phases Li2AgSb, LiMgSb, and Li3Sb.

Sputter Growth of Alkali Antimonide Photocathodes: An in Operando Materials Analysis

Abstract: Alkali antimonide photocathodes are a strong contender for the cathode of choice for next-generation photon sources such as LCLS II or the XFEL. These materials have already found extensive use in photodetectors and image intensifiers. However, only recently have modern synchrotron techniques enabled a systematic study of the formation chemistry of these materials. Such analysis has led to the understanding that these materials are inherently rough when grown through traditional sequential deposition; this roughness has a detrimental impact on the intrinsic emittance of the emitted beam. Sputter deposition may provide a path to achieving a far smoother photocathode, while maintaining reasonable quantum efficiency. We report on the creation and vacuum transport of a K2CsSb sputter target, and its use to create an ultra-smooth (sub nm roughness) cathode with a 2% quantum efficiency at 532 nm.

2.2–2.7 μm side wall corrugated index coupled distributed feedback GaSb based laser diodes

Abstract: We report on the modeling, growth, processing, characterization and integration in a gas detection setup of side wall corrugated distributed feed-back antimonide diode lasers emitting at 2.28 and 2.67 μm. The laser structures were grown by molecular beam epitaxy on GaSb substrate. Ridge lasers were fabricated from the grown wafers according to the following process: a second order Bragg grating was defined on the sides of the ridges by interferometric lithography, optical lithography and etched in a Cl-based inductively coupled plasma reactor. The devices exhibit a power reaching 40 mW, a side mode suppression ratio better than 28 dB and a tuning range of 3 nm at room temperature. One of these devices was successfully integrated in a tunable diode laser absorption spectroscopy setup, thus demonstrating that they are suitable for gas analysis.

Wet Chemical Etching of Antimonide-Based Infrared Materials

Abstract: The roughness and the crystallographic orientation selectivity of etched antimonide-based infrared materials are examined and are used to optimize the chemical mesa etching process of the InAs/GaSb superlattice photodiode with the goal of reducing the dark current. The etchant used is based on phosphoric acid (H3PO4), citric acid (C6H8O7) and hydrogen peroxide (H2O2). The roughness of the mesa sidewalls and etching rates are compared and used to find an optimized etchant, with which we obtain optimized mid-wavelength infrared photodiodes possessing an R0A value of 466 ωcm2 and a detectivity of 1.43 × 1011 cmHz1/2 W−1. Crystallographic orientation selectivity is seen in InAs etching, and also is seen in the InAs/GaSb superlattice wet chemical etching process.

Anodic fluoride passivation of type II InAs/GaSb superlattice for short-wavelength infrared detector

Abstract: One of the major challenges of antimonide-based devices arises owing to the large number of surface states generated during fabrication processes. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of this material system. In this paper, we proposed a new passivation method (zinc sulfide coating after anodic fluoride) for InAs/GaSb superlattice infrared detectors. InAs/GaSb superlattice short-wavelength infrared materials were grown by molecular beam epitaxy on GaSb (100) substrates. A GaSb buffer layer, which can decrease the occurrence of defects with similar pyramidal structure, was grown for optimized superlattice growth condition. High resolution X-ray diffraction indicated that the period of the superlattice corresponding to fourth satellite peak was 39.77 A. The atomic force microscopy images show the roughness was below 1.7 nm. The result of photoresponse spectra shows that the cutoff wavelength was 3.05 μm at 300 K.

(Invited) Dilute-Nitride-Antimonide Materials Grown by MOVPE for Multi-Junction Solar Cell Application

Abstract: We have investigated the growth by metalorganic vapor phase epitaxy (MOVPE) of multinary (fourand fiveelement) dilutenitride-antimonide materials on GaAs substrates. The lowest background carbon concentration (~ 5 × 10 cm) is observed in dilute-nitride materials grown at high temperature which do not contain Sb (i.e. InGaAsN). An increased depletion region width significantly improves the solar cell performance over that found from dilute-nitride cells grown at lower growth temperatures (~525C). The device performance of the single-junction solar cells with the low carbon background InGaAsN base region (InGaAsN/Ge double-junction solar cell) exhibit short-circuit current density, open-circuit voltage, fill factor, and efficiency values of 26.05 (28.46) mA/cm, 0.67 (0.9) V, 75.85 (72.8) %, and 13.2 (18.54) %, with anti-reflecting coating (ARC), respectively.

Multiple-junction photovoltaic cell based on antimonide materials

Abstract: The invention relates to a photovoltaic cell that can be used under high levels of solar concentration (≥1000 suns). The cell according to the invention consists of a cell comprising at least one junction produced on a substrate based on gallium antimonide, said at least one junction comprising two alloys based on an antimonide material (Ga 1-x Al x As y Sb 1-y ) lattice-matched on the substrate GaSb. If there are several junctions, two neighbouring junctions are separated by a tunnel junction.

The Electron Scattering on Local Potential of Crystal Defects in GaSb Whiskers

Abstract: Gallium antimonide based materials provide a wide range of electronic band gaps, electronic barriers along with extremely high electron mobility and therefore have been studied extensively in recent years for potential device applications in a variety of mid-infrared lasers, detectors and extremely low-power high-speed electronic devices [1-4]. But to take full advantage of the potential and functionality of antimonide-based devices, it is desirable to grow the epitaxial layers or QDs on a lattice-matched semi-insulating substrate. However, an influence of substrate substantially restricted the advantages of material free-standing nanoand microwhiskers are used to avoid shortcoming a growth of GaSb ingots. For the transport phenomena description in this semiconductor long-range scattering models of charge carriers is mainly used. According to this models charge carrier should interacts with all the crystal (electron-phonon interaction) or with the defect potential of the impurity with the action radius equal to  10-1000 а0 (а0 – lattice constant). But the charge carrier must interact with neighbouring crystal region in conformity with special theory of relativity. Moreover above-mentioned theories are considered in the first approximation of perturbation theory whereas the defect potential becomes the second order of the magnitude for defects with the interaction energy

Cobalt-antimonide-base thermoelectric film and preparation method thereof

Abstract: The invention discloses a cobalt-antimonide-base thermoelectric film and a preparation method thereof. The preparation method comprises the following steps: by using a cobalt antimonide target as a sputtering target, and separately making a material to be doped into a doping target; fixing the sputtering target and doping target to a rotating target rack of a multi-station sputtering system for later sputtering; and plating a cobalt antimonide film on an insulating substrate by sputtering deposition while sputtering the doping material on the antimonide cobalt film by many times to obtain a laminated-structure film, and finally, carrying out in-situ heat treatment to obtain the cobalt-antimonide-base thermoelectric film. The method has high controllability, and is beneficial to generation of the film structure; the film has favorable adhesiveness and repetitiveness, can satisfy the demands for large-scale production, and can accurately control the sputtering power, time and other parameters as well as the doping amount of the doping material; and by adopting the lamination mode, multiple elements can be simultaneously doped conveniently, and the complex techniques for preparing the multi-doping-element target are reduced.

Physics and technology of antimonide heterostructure devices at SCD

Abstract: SCD has developed a range of advanced infrared detectors based on III-V semiconductor heterostructures, grown on GaSb. The XBn/XBp family of detectors enables diffusion limited behavior with dark currents comparable with MCT Rule-07 and with high quantum efficiencies. InAsSb/AlSbAs based XBn focal plane array detectors with a cut-off wavelength of ~ 4.1 μm and formats presently up to 1024×1280 / 15 μm, operate with background limited performance up to ~175 K at F/3. They have a sensitivity and image quality comparable with those of standard InSb detectors working at 77K. In an XBp configuration, the same concept has been applied to an InAs/GaSb type II superlattice (T2SL) detector with a cut-off wavelength of ~ 9.5 μm, which operates with background limited performance up to ~100 K at F/2. In order to design our detectors effectively, a suite of simulation algorithms was developed based on the k ⋅ p and optical transfer matrix methods. In a given T2SL detector, the complete spectral response curve can be predicted essentially from a knowledge of the InAs and GaSb layer widths in a single period of the superlattice. Gallium free T2SL detectors in which the GaSb layer is replaced with InAs1-xSbx (x ~ 0.15-0.5) have also been simulated and the predicted spectral response compared for the two detector types.

Method for heteroepitaxial growth of antimonide semiconductor on macrolattice dismatch substrate

Abstract: The invention relates to a method for heteroepitaxial growth of an antimonide semiconductor on a macrolattice dismatch substrate and belongs to the technical field of semiconductor material preparation. The method provided by the invention comprises the following steps: before growing the antimonide semiconductor, pre-depositing an aluminum (or AlSb) thin layer on a silicon substrate by virtue of other physical deposition (such as magnetron sputtering) thin film preparation techniques; then, loading a sample in an MOCVD system for epitaxial growth; before growth, just introducing a Sb organic source; then annealing in position for antimonide of the aluminum (or AlSb) thin layer so as to form a stable AlSb buffer layer structure; and when the antimonide starts to grow, lifting the cover degree of the antimonide semiconductor by virtue of the existing AlSb buffer layer structure. In the whole growing process, the organic aluminum source is not introduced into the MOCVD system, so that aluminum pollution of equipment is avoided. The method can be used for not only enhancing the surface cover degree of the antimonide on the macrolattice dismatch substrate, but also avoiding the memory effect of the aluminum source in the equipment.

Improving the Smoothness of Multialkali Antimonide Photocathodes: An In-Situ X-Ray Reflectivity Study

Abstract: Multialkali antimonide photocathodes have been shown to be excellent electron sources for a wide range of applications because of high quantum efficiency, low emittance, good lifetime, and fast response. In recent years, synchrotron X-ray methods have been used to study the growth mechanism of K2CsSb photocathodes. The traditional sequential growth of K2CsSb has been shown to result in rough surface, which will have an adverse impact on the emittance of the electron beam. However, coevaporation of alkali metals on the evaporated Sb layer and sputter deposition may offer a route to solving the roughness problem. Recent studies on K2CsSb grown by these methods are presented and surface roughness is determined by X-ray reflectivity (XRR) and results are compared.

Transverse-mode selectivity in antimonide-based vertical-cavity surface-emitting lasers

Abstract: In this work results of a threshold operation of antimonide-based tunnel-junction (TJ) VCSEL have been presented with the aid of the comprehensive fully self-consistent optical-electrical-thermal-recombination numerical model. Calculations have been carried out for the structure with GaInAsSb/GaSb active region emitting at 2.6 µm. In order to suppress higher-order transverse modes in the device three different methods have been used. It has been shown that each of these methods allows us to achieve lasing with the LP 01 mode for structure with TJ diameter of 8 µm, which has not been possible for the structure without modifications. Although using these methods leads to higher values of the threshold current, the drop of the maximal operating temperature for the structure with TJ diameter of 7 µm has not been higher than 10 K.

Preparation method for vertical III-V family antimonide semiconductor monocrystalline thin film

Abstract: The invention provides a preparation method for a vertical III-V family antimonide semiconductor monocrystalline thin film. The preparation method comprises the steps that step (a): multiple metal catalyst particles used for catalyzing nanowire growth are prepared on a semiconductor substrate; step (b): growth of III-V family semiconductor nanowires is catalyzed on the semiconductor substrate by utilizing the metal catalyst particles, and the metal catalyst particles are arranged at the top end of the III-V family semiconductor nanowires; and step (c): epitaxy of the vertical III-V family antimonide semiconductor monocrystalline thin film is performed on the axial direction of the III-V family semiconductor nanowires so that preparation is completed. Mass production of the vertical III-V family antimonide semiconductor monocrystalline thin film can be easily realized by the preparation method so that production cost of the III-V family antimonide semiconductor monocrystalline thin film can be greatly saved.

Gratings preparation of 2μm antimonide distributed feedback laser diode

Abstract: This paper designed the period, depth and duty cycle of second-order Bragg grating. The grating is fabricated on GaSb substrate by holographic photolithography and wet etching. Images of scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that the grating has a period of 528nm, duty cycle of 0.25, depth of 109nm, the graphic shows an ideal sinusoid with favourable continuity and uniformity.

DC Analysis of InP/GaAsSb DHBT Device

Abstract: Tremendous increment in the high speed demands of data rate results in the continuous development in Type II InP/GaAsSb/InP Dual Heterojunction Bipolar Transistor Device. Physical based two dimensional device simulators, Atlas tool is used to study the DC operation and performance of InP/GaAsSb Dual Heterojunction Bipolar Transistor Device approaching Giga Hertz frequency range. Gallium Arsenide Antimonide lattice matched to Indium Phosphide is the replacement of Indium Gallium Arsenide based DHBTs because of its non collector blocking effect. Simulated device has shown a dc peak current gain of 70-80 dB, turn on voltage of 0.1V for 0.5 x 1 µm 2 emitter device having 15nm thick uniform GaAsSb base. Keywords - Double Heterojunction Bipolar Transistor (DHBTs), Indium phosphide (InP),Gallium Arsenide Antimonide (GaAsSb) ,Indium Gallium Arsenide (InGaAs), Heterojunction Bipolar Transistor (HBTs), maximum oscillation frequency (fMAX), cutoff frequency (fT).