Indium Antimonide Crystals Research Articles

Charge carrier transport and electrical response by driving band gap modulation in semiconductors

Electrical responses and carrier transport dynamics in intrinsic bulk semiconductors are found when a variable gradient in a physical property or field causes a gradient in the band gap and, in turn, in the carrier concentrations. A variable carrier concentration profile leads to a dynamic carrier diffusion flow. The electrical responses depend on temperature and the difference between electron and hole mobilities. This novel effect is evaluated for both open-circuit and closed-circuit configurations. One example is a variable carrier concentration created by acoustically stimulated band gap modulation. A standing acoustic wave in the lattice produces a dynamic pressure-induced variable band gap modulation. Responses from an indium antimonide crystal in acoustic resonance with amplitude of 2.23 MPa (rms) are found to be in the ranges of 30–40 mA and 0.1–0.3 mV for closed and open circuit cases, respectively. At room temperature, quantum effects do not contribute significantly to the description of carrier behavior and transport, except for scattering. The effect can also be produced by perturbations other than pressure if the band gap depends on those perturbations. The electrical responses characteristic of these semiconductors can be used for developing new sensors or transducers to measure gradients, such as pressure gradient transducers.

Spin-Phonon Magnetic Resonance of Conduction Electrons in Indium Antimonide Crystals

Resonance absorption of radio waves (with a frequency of 10 MHz) by c-band electrons in indium antimonide crystals doped with hydrogen-like donors (tellurium atoms) at room temperature in an external magnetic field is theoretically studied. Known experimental data obtained for samples with electron concentrations in the range from 6∙1015 to 5∙1018 cm–3 are analyzed and interpreted. Resonant absorption of radio waves by n-InSb:Te crystals in a magnetic field is calculated to be due to spin-phonon resonance based on the law of conservation of energy and the quasi-wave vector for electrons and optical phonons. The resonance arises as a result of a spin-flip interaction of a c-band electron with an optical phonon, which is assisted by resonant absorption of radio waves in a magnetic field. A physical picture of the phenomenon is given. Analytical relations are presented. Calculations are carried out and are consistent with experimental data that could not previously be interpreted at all.

Localization by an external magnetic field of electrons on the ions of hydrogen-like donors in non-degenerate semiconductors

In the quasi-classical approximation of quantum mechanics a model for the localization of conduction electrons on the ions of hydrogen-like donors in an external magnetic field was developed. The thermal ionization energy of donors in lightly doped and moderately compensated crystals of gallium arsenide and indium antimonide of n-type was calculated depending on the induction of the external magnetic field. In contrast to the known theoretical works (which use variational methods for solving the Schrödinger equation), a simple analytical expression is proposed for the ionization energy of the donor in the magnetic field, which quantitatively agrees with the known experimental data. It is shown that the magnitude of the magnetic field induced by the orbital motion of the electron around the ion core of the donor is negligible compared to the external field and does not contribute to the ionization energy of donors.

Modeling the Vibrational Properties of InSb Diamondoids and Nanocrystals Using Density Functional Theory

Raman and infrared spectra were used to obtain the vibrational properties of an indium antimonide crystal. The density functional theory of the Perdew, Burke and Ernzerhof functions/3-21G and the functions’ basis of polarization were employed. This study investigates how the vibrational frequencies of InSb diamondoids change with size as compared to the experimental bulk. The results showed that the bond lengths in InSb diamondoids decreased as the number of atoms within increased. Many physical properties were studied, including energy gaps, tetrahedral angles, dihedral angles, atomic charges, and bond lengths. The high reduced mass mode (HRMM) and high force constant mode were found to be larger in octamantane than in diamondoids, at 211.09 cm−1 and 190.17 cm−1, respectively.

Communication: Demonstration of a 20 ps X-ray switch based on a photoacoustic transducer.

We have studied an X-ray switch based on a gold coated indium antimonide crystal using time-resolved X-ray diffraction and demonstrated that the switch could reduce the pulse duration of a 100 ps X-ray pulse down to 20 ps with a peak reflectivity of 8%. We have used a dynamical diffraction code to predict the performance of the switch, which was then confirmed experimentally. The experiment was carried out at the FemtoMAX beamline at the short-pulse facility of the MAX IV laboratory. The performance and limitation of the switch are discussed in terms of acoustic transport properties between the two materials and the electron transport properties of gold.

Grain Growth Studies of Indium Antimonide Thin Films and Its Application in photovoltaic cell

Compound III-V materials are formed when atoms from group Illb of the periodic table combine with atoms from group Vb. The resulting com pounds are both crystalline and semiconducting and contain an equal proportion of both atom types. The Indium antimonide crystal has been used for infrared applications and for the radiation detector applications. Thin films of InSb with a thickness of about 0.12 micrometer are prepared onto well-cleaned glass substrates by employing an e- beam evaporation process. Indium Antimonide thin films are grown onto well cleaned glass substrates at room temperature on cleaned glass substrate in Hind Hivac- Vacuum Coating unit under a vacuum better than 10<sup>−5</sup> Torr. X-ray diffraction studies confirm the polycrystalline of the films and the films show preferential orientation along the (111) plane. The particle size found to about 1100 micrometer of thin film. In this paper we present some of our results concerning the synthesis and crystal growth of indium antimonide compounds . To carry out the synthesis of InSb a suitable mixing furnace was designed and fabricated.

Performance estimation of InSb compound semiconductor detectors as a function of active area using alpha particles

We have fabricated radiation detectors using p-type indium antimonide crystals grown by liquid phase epitaxy (LPE). The current–voltage curves, energy spectra of alpha particles, and energy resolutions obtained using two different InSb detectors were compared. The alpha-particle energy resolutions were 1.8% at 24 and 42K, using the LPE–InSb detector with wafer size of 1.0×1.5mm2.

Autosolitons in low-resistivity indium antimonide and tellurium single crystals in a magnetic field

It is experimentally shown that longitudinal autosolitons excited by the Joule heating of low-resistivity p-InSb (p ≈ 1013 cm−3) and p-Te (p ≈ 1014 cm−3) samples in a high electric field are insensitive to magnetic fields. This is due to diamagnetism induced in longitudinal autosolitons by self-pinching. Similar behavior of longitudinal autosolitons is observed in high-resistivity p-InSb (p ≈ 1012 cm−3) samples with diamagnetism produced in the case of θ pinching in an external longitudinal magnetic field.

Evolution of growth and enhancement in power factor of InSb bulk crystal

Indium antimonide crystals were synthesized from the respective component elements using the vertical Bridgman technique. The grown crystals were characterized by using X-ray analysis, EDX, electrical conductivity and thermoelectric power measurements. The calculated structural parameters for the prepared crystal have a good agreement with the standard values. Crystallite size (D) of the obtained InSb crystals was calculated to be 62.4 nm. The measurements reveal higher values for Seebeck coefficient, electrical conductivity and power factor than the published results for the same compound.

PROPERTIES OF OPTICAL WINDOWS FOR IR SENSORS

Properties of IR sensor windows which are used for the photodetectors working in conditions of hard radiation are investigated. Germanium, gallium arsenide and indium antimonide crystals windows property change is investigated. It is shown, that such changes depend on initial properties and occurrence of structural defects.

Magnetophotoluminescence of neutral acceptor states in InSb

Magnetophotoluminescence experiments on n-type bulk indium antimonide crystals have been performed using a cryogenically cooled interferometer. Both donor–acceptor-pair and free electron-to-neutral acceptor recombination transitions have been observed for four distinct acceptor species. Despite the small difference in the cadmium and germanium binding energies, the high-resolution photoluminescence experiments presented were able to resolve the two acceptors. Acceptor binding energies for Cd, 72.3 cm−1 (8.96 meV), and Ge, 69.0 cm−1 (8.55 meV), are consistent with previously published results. Two unknown acceptors having binding energies of 99.6 cm−1 (12.35 meV) and 161.9 cm−1 (20.07 meV) are also discussed.

Design and performance of the double crystal monochromator beamline at the Canadian Light Source

The medium energy x-ray double crystal monochromator (DCM) is currently being designed at the Canadian Light Source (CLS). Design goals for the DCM are to provide photons between 1750–5500 eV with a resolving power better than 3000 and photon flux better than 5×1010 photons/s/0.1% bandwidth for 500 mA beam current. A set of indium antimonide crystals [InSb(111)] will be used over the energy range of 1750–3700 eV, with resolution ranging from 0.52–1.05 eV. Although InSb allows one to probe the important silicon K edge at ∼1840 eV, it has the disadvantage of poor thermal conductivity. Exposure to high heat loads from the CLS synchrotron on the first crystal (∼56.5 W of power for 2 mrad of horizontal bending magnet radiation, ∼0.54 W/mm2 power density) will cause crystal distortion and thereby intensity/resolution degradation. A second set of silicon crystals [Si(111)] are proposed for the energy range of 3700–5500 eV. Resolution ranges linearly from ∼0.41 to ∼0.70 eV over this energy range. A harmonic filter mirror has been included in the design to reject higher harmonic orders. SHADOW ray-tracing results show that the experimental focus should be 334 μm [horizontal full width at half-maximum (FWHM)]×296 μm (vertical FWHM) when the CLS is operational under 2008 conditions.

Growth and characterization of indium antimonide and gallium antimonide crystals

Indium antimonide and gallium antimonide were synthesized from the respective component elements using an indigenously fabricated synthesis unit. Bulk crystals of indium antimonide and gallium antimonide were grown using both the vertical and horizontal Bridgman techniques. Effect of ampoule shapes and diameters on the crystallinity and homogeneity was studied. The grown crystals were characterized using X-ray analysis, EDAX, chemical etching, Hall effect and conductivity measurements. In the case of gallium antimonide, effect of dopants (Te and In) on transport and photoluminescence properties was investigated.

Growth of inclusion-free InSb crystals by vertical Bridgman method

Inclusions were observed in indium antimonide crystals grown by the vertical Bridgman technique. The presence of these inclusions depends on several factors such as synthesis temperature, synthesis time, thermal gradient, ampoule lowering rate and ampoule geometry. These inclusions were analysed by electron probe microanalysis. Series of experiments were carried out to optimise the growth conditions to obtain inclusion-free InSb crystals.

Bulk growth of InSb crystals for infrared device applications

High-quality indium antimonide crystals, suitable for infrared device applications, were grown by vertical Bridgman technique. An indigenous Bridgman setup with some modifications was employed for this purpose. A series of experiments were carried out with different ampoule lowering rate, axial temperature gradient and ampoule cone angle in order to optimise the growth conditions. The grown crystals were subjected to XRD and EDX analyses to assess chemical homogeneity. Chemical etching revealed no observable variation in defect-density distribution. Electrical properties were also studied along the length of the crystal. IR transmittance studies, carried out on a sample 1.5 cm in diameter and 300 μm in thickness, revealed the high-percentage transmittance and sharp cutoff at shorter wavelength end which are the essential conditions for an infrared filter.

Effect of non-centrosymmetry on Stark broadening in bulk indium antimonide crystal

Stark shift and self-energy correction in a non-centrosymmetric semiconductor have been studied by using the time-dependent perturbation technique and considering the diagonal elements of the transition dipole moment operator to be finite. The Stark shift obtainable from the Rabi frequency shows a time dependence. The analysis is applied to a sample of InSb duly irradiated by a near-resonant laser and it is found that the magnitude of Stark shift decreases while the magnitude of self-energy correction increases due to the incorporation of non-centrosymmetry.

Interface Dynamics during Indium Antimonide Crystal Growth

Experiments with a stoichiometric InSb compound were first performed at small temperature gradient across the crystal/melt interface of 3 °C/cm and furnace translation velocity, Vfrn, of 2 μ/sec. Known growth requirements for quality crystals were confirmed. They are, (1) the interface temperature must be close to the congruent melting temperature and, (2) the interface must be located within the adiabatic zone. These requirements can be obtained only through specific settings of the heater temperatures. An X-ray radioscopic system has been modified to accommodate real-time visualization of the crystal/melt interface during vertical Bridgman-Stockbarger growth of InSb. It is shown that asymmetric temperature settings of the heaters can be advantageously used to minimize defect formation. The interface temperature was assessed indirectly with calibrated outside thermocouples. Optical microscopy and electron microprobe analyses provided feedback on crystalline homogeneity.

Magnetically stabilized electron-hole liquid in indium antimonide

Luminescence spectra of sufficiently pure n-type indium antimonide crystals (ND−NA=(1–22)·1014 cm−3) in a magnetic field of up to 56 kOe, at temperatures of 1.8–2 K, and high optical pumping densities (more than 100 W/cm2) have been studied. More evidence of the existence of electron-hole liquid stabilized by magnetic field has been obtained, and its basic thermodynamic parameters as functions of magnetic field have been measured. When the magnetic field increases from 23 to 55.2 kOe, the liquid density increases from 3.2·1015 to 6.7·1015 cm−3, the binding energy per electron-hole pair rises from 3.0 to 5.2 meV, and the binding energy with respect to the ground exciton level (work function of an exciton in the liquid) rises from 0.43 to 1.2 meV.

Self-diffusion in indium antimonide

In the present paper indium and antimony self-diffusion was studied in the temperature range 400–500 °C in single crystals of indium antimonide. The crystals were grown by the Bridgman technique. The radioactive tracer diffusion method was employed using In114m and Sb125 isotopes. Anodic oxidation technique was developed and used for serial sectioning. The penetration profiles were fitted to the error function solution of diffusion equations. For indium self-diffusion, the activation energy and pre-exponential factor were found to be 1.45 eV and 6.0×10−7 cm2/s, respectively, while for antimony diffusion the activation energy was obtained as 1.91 eV with a pre-exponential factor of 5.35×10−4 cm2/s. The results were compared with the earlier experimental studies and theoretical calculations. The migration enthalpies of indium and antimony atoms are estimated to be 0.66 and 0.70 eV, respectively. The corresponding formation enthalpies are 0.79 eV for In vacancy and 1.21 eV for Sb vacancy formation.

Development of a high resolution cryogenic detector with applications in β spectroscopy and solar ν searches

The characteristics of a high resolution cryogenic detector, at an operating temperature of 100 mK, are presented. The detector consists of a series array of superconducting aluminium tunnel junctions fabricated on a 1 g single crystal of indium antimonide. The array is sensitive to the phonons generated by nuclear particle interactions in the semi-conducting InSb substrate. The intrinsic energy resolution of the device, on irradiation by 22.1 keV X-rays, corresponds to 206 eV (full width at half maximum) after the removal of electronic noise. The threshold for energy detection is 300 ev. The linearity properties of the detector are well demonstrated over the range of energies, 3 to 662 keV. Preliminary results are presented of the response of the detector to a 63Ni β source in a sandwich geometry. The question of the extension of such a detector to a solar ν experiment is addressed.