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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic properties of Pr-Fe-B alloy powders prepared by mechanical grinding : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6591-6593 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of ball milling on the magnetic properties of the Pr15Fe80B5 alloy, whose as-cast structure was composed of matrix phase Pr2Fe14B and Pr-rich and α-Fe phases, has been investigated by measuring iHc, thermomagnetic curves, and x-ray diffraction (XRD) patterns. By ball milling using a planetary ball mill up to 96 h, iHc decreased with the amorphization of the matrix and Pr-rich phases. However, subsequent heat treatments gave rise to the marked increase of iHc. The alloy, after 48 h of ball milling and subsequent 600 °C annealing possessed iHc of 17.4 kOe, Br of 5.8 kG, and (BH)max of 6.5 MGOe. This alloy showed sharp diffraction peaks of Pr2Fe14B phase, while the α-Fe phase peak, which persisted through the ball milling process, almost disappeared. The high iHc of the Pr-Fe-B alloy, subjected to optimum milling and subsequent annealing, was attributed to a very fine Pr2Fe14B phase precipitation from the amorphous state and to the effective solution of the α-Fe phase into the matrix phase. Also, a small addition of Cu to the Pr15Fe80B5 alloy was found to increase the coercivity. Further, the alloy milled for 12 h and annealed at 600 °C for 1 h showed iHc of 19.7 kOe, Br of 7.0 kG, and (BH)max of 10.2 MGOe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349867
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular-beam epitaxy growth and in situ arsenic doping of p-on-n HgCdTe heterojunctions (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2143-2148 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we present, results on the growth of in situ doped p-on-n heterojunctions on HgCdTe epilayers grown on (211)B GaAs substrates by molecular-beam epitaxy (MBE). Long wavelength infrared (LWIR) photodiodes made with these grown junctions are of high performance. The n-type MBE HgCdTe/GaAs alloy epilayer in these structures was grown at Ts=185 °C and it was doped with indium (high 1014 cm−3 range) atoms. This epilayer was directly followed by the growth, at Ts=165 °C, of an arsenic-doped (1017–1018 cm−3 ) HgTe/CdTe superlattice structure which was necessary to incorporate the arsenic atoms as acceptors. After the structure was grown, a Hg annealing step was needed to interdiffuse the superlattice and obtain the arsenic-doped p-type HgCdTe layer above the indium-doped layer. LWIR mesa diodes made with this material have 77 K R0A values of 5×103, 81, 8.5, and 1.1 Ω cm2 for cutoff wavelengths of 8.0, 10.2, 10.8, and 13.5 μm, respectively; the 77 K quantum efficiency values for these diodes were greater than 55%. These recent results represent a significant step toward the demonstration of MBE as a viable growth technique for the in situ fabrication of large area LWIR focal plane arrays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348741
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  • 3
    Electronic Resource
    Electronic Resource
    Isothermal vapor-phase epitaxy of Hg1−xCdxTe on CdTe and Al2O3 substrates (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 4721-4726 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The isothermal vapor-phase-epitaxial (ISOVPE) growth of device-quality HgCdTe layers on both CdTe and CdTe/Al2O3 substrates has been demonstrated. The material and device properties on both types of substrates have been studied and compared with reported values for HgCdTe grown by other techniques. The as-grown ISOVPE Hg1−xCdxTe (x(approximately-equal-to)0.3) epilayers are always p type with carrier concentrations of ∼5×1015 to 3×1016 cm−3 and mobilities of ∼230–260 cm2/V s at 77 K. The temperature and compositional dependence of electrical properties of ISOVPE Hg1−xCdxTe are somewhat different from those of liquid-phase epitaxy (LPE) and bulk HgCdTe. In particular, the acceptor ionization energy, EA =7 meV, is about half that obtained in midwavelength infrared LPE or bulk HgCdTe, and nearly independent of composition x. The R0A product of a representative photodiode (λc (approximately-equal-to)4.65 μm, 77 K) is 2×106 and 4 Ω cm2 at 77 and 195 K, respectively, with comparable device qualities seen on both CdTe and CdTe/Al2O3 substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335334
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  • 4
    Electronic Resource
    Electronic Resource
    Properties of dc magnetron sputtered indium tin oxide films on polymeric substrates at room temperature (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5199-5203 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Indium tin oxide (ITO) thin films were deposited on polymeric substrates at room temperature by dc reactive magnetron sputtering from an In–Sn (90–10 wt%) alloy target. The electrical, optical, and mechanical properties of ITO films on various substrates such as polycarbonate, acrylic, polyethylene terephthalate, and glass are influenced sensitively by sputtering parameters. Therefore, the dependence of these properties on dc power, working pressure, and partial oxygen content has been systematically investigated. Low dc power was applied to avoid the deformation of polymeric substrates. The electrical resistivity of as-deposited ITO films decreases initially and then increases as oxygen partial pressure (PO2) increases. The optical transmittance at visible wavelength of 550 nm was as much as 85%. The friction force of as-deposited ITO films on various substrates is increased with an increase of dc power, and behaves similarly to the optimum curve of resistivity with increasing PO2. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1357470
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  • 5
    Electronic Resource
    Electronic Resource
    Infrared photodiodes fabricated with Hg1−xCdxTe grown by molecular beam epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 39-41 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Device-quality Hg1−xCdxTe (0.26〈x〈0.33) epilayers with thicknesses in the range 10–20 μm were grown on (111)B CdTe substrates by molecular beam epitaxy (MBE). The as-grown layers were p type, and typically had carrier concentrations in the low 1016 cm−3 range and hole mobilities greater than 220 cm2/V s at 77 K. The n+-p junction was formed by Be ion implantation; unpassivated mesa photodiodes were fabricated by standard photolithographic techniques. Resistance-area products (R0A) at zero bias were 5.2×106 and 1.4×104 Ω cm2 at 77 K for Hg1−xCdxTe with cutoff wavelengths of 4.0 and 5.7 μm, respectively. These R0A values approach typical ones obtained by liquid phase epitaxy and represent a very promising initial effort for MBE-grown Hg1−xCdxTe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99310
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared diodes fabricated with HgCdTe grown by molecular beam epitaxy on GaAs substrates (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1025-1027 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared photodiodes fabricated with HgCdTe epilayers grown on GaAs substrates by molecular beam epitaxy (MBE) are reported here for the first time. Growth was carried out on the (211)B orientation of GaAs, and the as-grown epilayer (x=0.24) was p type. The n-p junction was formed by Be ion implantation, the resistance-area product (R0 A) at zero bias was 1.4×103 Ω cm2 , the wavelength cutoff was 8.0 μm, and the quantum efficiency was 22%; all were measured at 77 K. We show that in the diffusion regime diodes fabricated with MBE HgCdTe/GaAs have comparable R0 A product values to those made with HgCdTe grown by bulk techniques. This result discloses new possibilities for advanced monolithic HgCdTe devices based on GaAs integrated circuit technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100787
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  • 7
    Electronic Resource
    Electronic Resource
    Cation vacancy formation energies in liquid-phase-epitaxial Hg1−xCdxTe (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 1470-1473 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental measurements of the cation vacancy formation energies (Ef) of Hg1−xCdxTe were carried out by Hg-annealing and rapid quenching to room temperature, followed by Hall measurements at 77 K. Our observations show that one charge state vacancy is dominant, so that the fractional number n of cation vacancies at temperature T is related exponentially to the energy Ef required to create one vacancy, n=A exp(−Ef/kT). No appreciable temperature dependence of Ef due to temperature variation of the ionization levels and the self-consistent Fermi level is seen. Our measured value for the activation energy is found to be Ef=0.9±0.1 eV, for Hg1−xCdxTe with x=0.21, 0.3, and 0.43. This value is found to be nearly independent of Cd composition x. Theoretical calculations of the p-type carrier concentrations due to cation vacancies in Hg0.8Cd0.2Te yield results which are in good agreement with experimental data. These modeling calculations predict the cation vacancies to be predominantly doubly ionized species at 77 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336078
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  • 8
    Electronic Resource
    Electronic Resource
    Long and middle wavelength infrared photodiodes fabricated with Hg1−x CdxTe grown by molecular-beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1747-1753 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Long and middle wavelength infrared (LWIR, MWIR) p+-n photodiodes have been fabricated with Hg1−xCdxTe (0.20〈x〈0.30) grown by molecular-beam epitaxy (MBE). The epilayers were grown on (211)B lattice-matched ZnCdTe substrates. The surface morphology was smooth and free of in-plane twins. The Cd concentration (x) was uniform across the wafer, with standard deviations (Δx) as low as 0.0017. Structural properties were measured by double-crystal x-ray rocking curve and dislocation etching; FWHM values as low as 34 arcsec and etch pit density values as low as 1×105 cm−2 were measured. p+ -n homojunctions were formed by arsenic diffusion; unpassivated mesa photodiodes were fabricated by standard photolithographic techniques. MWIR and LWIR photodiodes fabricated with MBE material exhibited good diode performance, comparable to that obtained on photodiodes fabricated with the more matured technique of liquid-phase epitaxy. 77-K R0A products of the diodes measured were 6.35×107, 22.3, and 1.76 Ω cm2 with cutoff wavelengths of 4.66, 9.96, and 12.90 μm, respectively. The R0A product for a VLWIR photodiode was 1.36×102 Ω cm2 with a cutoff wavelength of 16.23 μm at 35 K. LWIR diodes with no antireflection coating had a quantum efficiency of 48.6%. The present results represent a significant step toward the demonstration of MBE as a viable growth technique for the fabrication of large infrared focal plane arrays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342925
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  • 9
    Electronic Resource
    Electronic Resource
    Minority carrier lifetime and diffusion length in HgTe/CdTe superlattices by molecular beam epitaxy (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1196-1198 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transient minority carrier lifetime and steady state diffusion length measurements have been performed on n-type HgTe/CdTe superlattices grown on CdZnTe(100) substrates. The n-type (100) superlattice sample shows a lifetime of 90–100 ns at 77–160 K which then decreases with increasing temperature down to 50 ns near 300 K. p-type HgTe/CdTe superlattices show normal behavior for temperature-dependent lifetimes. The measured lifetime is approximately 20 ns at 77 K and increases continuously to 85 ns at 300 K. An independent measurement of minority carrier diffusion length in a p-type HgTe/CdTe superlattice has led to an excellent agreement with a transient lifetime value of 66 ns at 200 K. The minority carrier diffusion length in a direction parallel to the interfaces indicates that the lateral transport properties are not much different from the transport properties of bulk HgCdTe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107592
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  • 10
    Electronic Resource
    Electronic Resource
    HgCdTe double heterostructure injection laser grown by molecular beam epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1022-1024 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: While a variety of light-detecting devices have been made with HgCdTe, little has been done to apply this technology to light-emitting devices. We report here the successful fabrication and operation of the first HgCdTe injection laser. This stripe-geometry double-heterostructure laser was operated under pulsed current at temperatures between 40 and 90 K. At 77 K, the emission wavelength was 2.86 μm with a linewidth of 0.3 meV, and the pulsed threshold current density was 625 A/cm2. The double heterostructure, with a 1.4-μm-thick active layer, was grown and in situ doped by molecular beam epitaxy (MBE). The p+ and n+ confinement layers were doped with arsenic and indium, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106332
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