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  • 1
    Electronic Resource
    Electronic Resource
    Quantum efficiency and spectral response of compositionally graded HgCdTe P-n heterojunction photodiodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4399-4406 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are presented of a study of the quantum efficiency of HgCdTe heterojunction photodiodes. All heterojunctions considered in the study consist of a wide-band-gap P-type layer and a narrow-band-gap n-type layer, and are illuminated from the backside. The n-type layer is compositionally graded and therefore contains a built-in electric field. Due to the difference in band gaps photons are absorbed in the active n-type layer only and are collected by both drift and diffusion mechanisms. The one-dimensional continuity equation is first solved in the linearly graded n-type region under illumination conditions, and then the dependence of the quantum efficiency on the resulting built-in electric field is presented. Two different modes of illumination are compared: In the first mode, associated with n-on-P HgCdTe diodes, the light reaches the transparent P layer first; in the second mode, associated with P-on-n diodes, the light reaches the transparent P side after it passes through the opaque n-type layer. The superiority of the first mode is demonstrated: It consistently renders higher quantum efficiencies, and is also less sensitive to several properties of the diode such as the width of the absorbing layer and the quality of the backside interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357333
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of built-in electric field on the performance of compositionally graded P-on-n HgCdTe heterojunction photodiodes (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 925-933 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of a study of the optical and electrical performance of P-on-n HgCdTe heterojunctions, with a linear gradient in composition, are presented. First presented is a solution of the one-dimensional continuity equation which includes the spatial dependencies of the material properties, such as absorption coefficient, band gap, and intrinsic carrier concentration, in the graded layer. Using the above solution, diodes with different grading profiles (and hence different electric fields), but with the same cutoff wavelength, are compared. The advantages of the built-in electric field formed by the grading in composition are presented and discussed. It is shown that the major consequence of the electric field is the reduction of the effects caused by the imperfect CdTe/HgCdTe interface at the backside. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359020
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  • 3
    Electronic Resource
    Electronic Resource
    The cutoff wavelength and minority-carrier lifetime in implanted n+-on-bulk p Hg1−xCdxTe photodiodes (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 2435-2439 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The cutoff wavelength λco at 77 K of implanted n+-on-bulk p-type Hg1−xCdxTe photodiodes is calculated with the minority-carrier lifetime of the bulk material as a parameter: 1.24/λco=[T+81.9/3.267×104(1+x)] {18.88−53.61x− 1/2 ln [(kT/q) μnτn]} −0.3424+1.838x+0.148x4 (eV). The composition x is obtained from the zero-intercept transmission spectra measured at 300 K. The minority-carrier lifetime τn of the photodiodes and its temperature dependence have been obtained from the photodiode dynamic resistance at zero-bias voltage versus reciprocal temperature 1/T data. The temperature dependence of the minority-carrier mobility μn is also taken into account. The results indicate that the lifetime in the bulk p-type material is determined by Shockley–Read generation-recombination centers. For undoped, p-type substrates obtained from Cominco Inc., the trap energy is approximately 45 meV. Gold-doped crystals grown by the method of solid-state recrystallization exhibit a trap energy of the order of 30–35 meV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341039
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  • 4
    Electronic Resource
    Electronic Resource
    Photoemission spectromicroscopy: A new insight in the chemistry of SnOx films for gas sensors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3997-4003 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We used the novel experimental technique of photoemission spectromicroscopy to investigate the active area of SnOx thin films for gas sensors, deposited by dc sputtering. First, we analyzed the degree of oxidation and the homogeneity of as-deposited films in a high lateral resolution (30 μm) spectromicroscopy mode with an energy resolution of 0.4 eV. This led to a surprising discovery of a large amount of tin monoxide on the film surface. Then we studied the interaction of H2 and H2O with the surface of polycrystalline SnO2 films used as sensitive layers in actual gas sensor devices. These results have been related to the resistivity changes of the corresponding devices: we found that such changes are primarily due to a reduction process in the film rather than to mere chemisorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352865
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  • 5
    Electronic Resource
    Electronic Resource
    The quantum efficiency of HgCdTe photodiodes in relation to the direction of illumination and to their geometry (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3034-3040 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper a theoretical study of the effect of the direction of the incident light on the quantum efficiency of homogeneous HgCdTe photodiodes suitable for sensing infrared radiation in the 8–12 μm atmospheric window is presented. The probability of an excess minority carrier to reach the junction is derived as a function of its distance from the edge of the depletion region. Accordingly, the quantum efficiency of photodiodes is presented for two geometries. In the first, the light is introduced directly to the area in which it is absorbed (opaque region), while in the second, the light passes through a transparent region before it reaches the opaque region. Finally, the performance of the two types of diodes is analyzed with the objective of finding the optimal width of the absorption area. The quantum efficiency depends strongly on the way in which the light is introduced. The structure in which the radiation is absorbed following its crossing the transparent region is associated with both higher quantum efficiency and homogeneity. In addition, for absorption region widths higher than a certain minimum the quantum efficiency in this case is insensitive to the width of the absorption region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351513
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  • 6
    Electronic Resource
    Electronic Resource
    The Syntheses of cis- and trans-Δ4-Tetrahydrohomophthalic Acids (1964)
    s.l. : American Chemical Society
    The @journal of organic chemistry 29 (1964), S. 3154-3158 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo01034a007
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  • 7
    Electronic Resource
    Electronic Resource
    Planar p-on-n HgCdTe heterostructure infrared photodiodes (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1331-1333 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a simple process to fabricate planar Hg1−yCdyTe/Hg1−xCdxTe (x〈y) heterostructure photodiodes with p-on-n configuration. The material used for this demonstration was a double-layer p-on-n heterostructure that was grown by a liquid-phase-epitaxy technique. The p-on-n planar devices consisted of an arsenic-doped p-type epilayer (y=0.28) on top of a long-wavelength infrared n-type epilayer (x=0.225, λ=10 μm). The ion-beam-milling p-to-n type conversion effect was used in order to delineate the active device element, and to isolate the planar device. Detailed analysis of the current–voltage characteristics of these diodes as a function of temperature show that they have high performance and that their dark current is diffusion limited down to 60 K. The results show that the R0A values are close to the theoretical limit over a wide range of cutoff wavelengths. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1353843
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  • 8
    Electronic Resource
    Electronic Resource
    Response to "Comment on ‘Electrical properties of epitaxially grown CdTe passivation for long-wavelength HgCdTe photodiodes' '' [Appl. Phys. Lett. 68, 2453 (1996)] (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2455-2455 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116318
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  • 9
    Electronic Resource
    Electronic Resource
    Estimation of HgCdTe band-gap variations by differentiation of the absorption coefficient (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2101-2103 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new simple nondestructive method for band-gap estimation in HgCdTe layers is presented in this work. The theoretical approach is based on a qualitative empirical model that assumes two different regions of absorption in HgCdTe. The border between the two regions, which indicates the approximate value of the band gap, is determined by differentiation of the absorption coefficient in respect to the photon energy. The approach is verified by experimental measurements on several HgCdTe layers grown by different techniques. First, the transmission is measured by Fourier transform infrared (FTIR) spectroscopy at room temperature; then, the measured data is smoothed and the absorption coefficient extracted. The absorption coefficient is then differentiated twice in respect to the photon energy which allows estimation of the average band gap and band-gap variations within the HgCdTe layer. It appears that this simple procedure can assist in monitoring the quality of HgCdTe layers and help predicting the cutoff wavelength of HgCdTe photodiodes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113916
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  • 10
    Electronic Resource
    Electronic Resource
    Electrical properties of epitaxially grown CdTe passivation for long-wavelength HgCdTe photodiodes (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2725-2727 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of experimental measurements and theoretical analysis are presented for the TiAu/ZnS/CdTe/HgCdTe metal–insulator–semiconductor heterostructure. The passivation of HgCdTe is provided by a double layer consisting of a dielectric ZnS placed on top of an epitaxial CdTe layer. Both HgCdTe and CdTe were grown by metalorganic chemical vapor deposition. Two types of CdTe layers were investigated: one was grown directly, in situ, immediately following the growth of HgCdTe; the second was grown indirectly using previously grown HgCdTe samples. It is shown that directly grown CdTe layers lead to low fixed interface charge, which is a good condition for passivation. The indirectly grown samples are still acceptable, but not as good as the directly grown samples. We demonstrate, on the basis of theoretical considerations, that the dielectric ZnS improves the flatband condition at the CdTe/HgCdTe interface. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112548
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