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  • 1
    Electronic Resource
    Electronic Resource
    Electron transport of inhomogeneous Schottky barriers: A numerical study (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 7403-7424 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical simulations are presented of the potential distribution and current transport associated with metal-semiconductor (MS) contacts in which the Schottky barrier height (SBH) varies spatially. It is shown that the current across the MS contact may be greatly influenced by the existence of SBH inhomogeneity. Numerical simulations indicate that regions of low SBH are often pinched-off when the size of these regions is less than the average depletion width. Saddle points in the potential contours in close proximity to the low-SBH regions, which are shown to vary with the dimension and magnitude of the inhomogeneity as well as with bias, essentially determine the electron transport across the low-SBH regions. It is these dependences of the saddle point which give rise to various abnormal behaviors frequently observed from SBH experiments, such as ideality factors greater than unity, various temperature dependences of the ideality factor, including the T0 anomaly, and reverse characteristics which are strongly bias-dependent. The results of these numerical simulations are shown to support the predictions of a recently developed analytic theory of SBH inhomogeneity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349737
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  • 2
    Electronic Resource
    Electronic Resource
    3, 4-Dimethylpyrazole phosphate reduces nitrous oxide emissions from grassland after slurry application (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 21 (2005), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. A field study was conducted to assess the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), applied at a rate of 1 kg ha−1, on nitrous oxide (N2O) emissions, forage production and N extraction from a grassland soil after cattle slurry applications in autumn and spring. Nitrous oxide emissions were measured daily or weekly using the closed chamber technique. DMPP efficiency after slurry application was lower in spring (16.7 °C mean soil temperature) than in autumn (11.4 °C mean soil temperature). Thus, DMPP was able to maintain soil mineral N in the ammonium form for 22 days and reduce cumulative N2O emissions by 69% in autumn, while in spring its effect on soil mineral N lasted for 7–14 days, reducing cumulative N2O losses by 48%. Furthermore, application of DMPP after slurry did not decrease biomass yield or N uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.2005.tb00106.x
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  • 3
    Electronic Resource
    Electronic Resource
    Mitigation of N2O emissions from grassland by nitrification inhibitor and Actilith F2 applied with fertilizer and cattle slurry (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 18 (2002), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Nitrous oxide (N2O) is involved in both ozone destruction and global warming. In agricultural soils it is produced by nitrification and denitrification mainly after fertilization. Nitrification inhibitors have been proposed as one of the management tools for the reduction of the potential hazards of fertilizer-derived N2O. Addition of nitrification inhibitors to fertilizers maintains soil N in ammonium form, thereby gaseous N losses by nitrification and denitrification are less likely to occur and there is increased N utilization by the sward. We present a study aimed to evaluate the effectiveness of the nitrification inhibitor dicyandiamide (DCD) and of the slurry additive Actilith F2 on N2O emissions following application of calcium ammonium nitrate or cattle slurry to a mixed clover/ryegrass sward in the Basque Country. The results indicate that large differences in N2O emission occur depending on fertilizer type and the presence or absence of a nitrification inhibitor. There is considerable scope for immediate reduction of emissions by applying DCD with calcium ammonium nitrate or cattle slurry. DCD, applied at 25 kg ha–1, reduced the amount of N lost as N2O by 60% and 42% when applied with cattle slurry and calcium ammonium nitrate, respectively. Actilith F2 did not reduce N2O emissions and it produced a long lasting mineralization of previously immobilized added N.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.2002.tb00231.x
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  • 4
    Electronic Resource
    Electronic Resource
    Nitrous oxide emissions from grassland in an intensive dairy farm in the Basque Country of Spain (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 17 (2001), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Intensively managed grasslands are potentially a large source of N2O in the North Coast of Spain because of the large N input, the wet soil conditions and mild temperatures. To quantify the effect of fertilizer type and management practices carried out by farmers in this area, field N2O losses were measured over a year using the closed chamber technique. Plots received two types of fertilizer: cattle slurry (536 kg N ha–1) and calcium ammonium nitrate (140 kg N ha–1). N2O losses were less in the slurry treatment than after mineral fertilizer. This was probably due to high, short-lived peaks of N2O encountered immediately following mineral N addition. In contrast, the seasonal distribution of N2O losses from the slurry amended plot was more uniform over the year. The greater N2O losses in the mineral treatment might have been enhanced by the combined effect of mineral fertilizer and past organic residues present from previous organic amendments. Weak relationships were found between N2O emission rates and soil nitrate, soil ammonium, soil water content and temperature. Better relationships were obtained in the mineral treatment than in the slurry plots, because of the wider range in soil mineral N. Water filled pore space (WFPS) was a key factor controlling N2O emissions. In the 〉 90% WFPS range no relationships were found. The best regressions were found for the mineral treatment in the 40–65% WFPS range, 49% of the variance being explained by soil nitrate and ammonium content. In the 65–90% WFPS range, 43% of the variance was explained by nitrate only, but the inclusion of soil ammonium did not improve the model as it did in the 40–65% WFPS range. This fact indicates that nitrification is likely to be an important process involved in N2O emissions at the 40–65% WFPS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.2001.tb00017.x
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of the electric relaxation in acrylate polymers with rigid side groups (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1906-1913 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The curves describing the temperature dependence of the dielectric loss for poly(4-acryloxyphenyl)–(4-chlorophenyl)–methanone exhibit a well developed subglass absorption followed in order of increasing temperature by an ostensible glass–rubber relaxation or α process. Free charge conductivity processes and blocking electrode phenomena become dominant in the α relaxation at frequencies below 10 Hz. An electric model is proposed to interpret the dielectric results covering the glassy state and the glass–rubber transition. The model is basically a parallel configuration involving a condenser (CΓα), a resistance (R), and a Havriliak–Negami-type impedance (ZHN*) coupled in series with an impedance (Ze*) representing the electrode phenomena. The circuit allows one to split the dipolar processes from both free charges and blocking electrode conductivity contributions to the real ε' and loss ε‘ parts of the complex dielectric permittivity at temperatures above the glass transition temperature of the polymer. At low frequencies the model predicts that ε' and ε‘ scale with frequency as ε'∼ω−(1+α¯) and ε‘∼ω−α¯, the exponent α¯ not being restricted to the conventional value of 0.5 commonly found in the literature. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360227
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  • 6
    Electronic Resource
    Electronic Resource
    The algebras of inhibited parafermionic violation of the Pauli principle (1993)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 34 (1993), S. 1110-1124 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The theory of the algebras of Ignat'ev and Kuz'min and of Greenberg and Mohapatra is developed. These are algebras of inhibited parafermionic oscillators that describe possible small violations of the Pauli exclusion principle. The cyclic modules of the algebras are constructed so as to exhibit the connection of their fundamental properties, as uniqueness and statistical signature, with the relations in the algebras. The formalism is presented in such a way suited for further mathematical and physical developments, and has a natural continuation in a forthcoming paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530241
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  • 7
    Electronic Resource
    Electronic Resource
    Representations of Kac–Moody and Virasoro algebras on modules of Greenberg–Mohapatra algebras (1993)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 34 (1993), S. 1125-1142 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The theory of Greenberg–Mohapatra algebras is developed in continuation to a previous paper. Standard cyclic modules are constructed for the algebras, and on them Kac–Moody and Virasoro algebras are represented through a basic procedure. The representations of Kac–Moody and Virasoro algebras help to understand the structure of Greenberg–Mohapatra algebras and the question of possible violation of the Pauli exclusion principle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530188
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  • 8
    Electronic Resource
    Electronic Resource
    Elimination of heterojunction band discontinuities by modulation doping (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 466-468 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conduction- or valence-band discontinuities occurring at the junction of two heterogeneous semiconductors can be eliminated by appropriate doping of the interfacial region. We show by analytic and self-consistent calculations that simultaneous modulation doping and parabolic compositional grading result in flat band-edge potentials. The new concept is applied to distributed Bragg reflectors for vertical cavity lasers. The structures grown by molecular-beam epitaxy exhibit significantly lower resistances as compared to step-graded distributed Bragg reflectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106636
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  • 9
    Electronic Resource
    Electronic Resource
    Scaling the Si metal-oxide-semiconductor field-effect transistor into the 0.1-μm regime using vertical doping engineering (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3315-3317 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conventional scaling of the Si MOSFET into the deep submicron regime requires high substrate doping levels. This extracts a severe speed penalty, if lower standby power consumption (i.e., good subthreshold behavior) is to be maintained. We explore the scaling of fully depleted silicon-on-insulator (SOI) structures, and show, both analytically and by numerical simulation, how the horizontal leakage is controlled by vertical doping engineering. Our analysis allows different structures to be evaluated in terms of a natural length scale indicating good subthreshold behavior. Finally, we describe how retrograde doping may be used to mimic the SOI concept in bulk Si. Our results show good subthreshold behavior in the deep submicron regime can be achieved without large junction capacitance, high threshold voltage, or heavy channel doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105717
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  • 10
    Electronic Resource
    Electronic Resource
    In situ arsenic-doped polycrystalline silicon as a low thermal budget emitter contact for Si/Si1−xGex heterojunction bipolar transistors (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 226-228 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A low thermal budget emitter contact with low specific contact resistivity (ρc) with the absence of transient enhanced diffusion (TED) effects is essential to fabricate integratable high performance Si/SiGe heterojunction bipolar transistors (HBTs). We report the use of in situ As-doped polycrystalline silicon (polysilicon) from a low base pressure rapid thermal episystem for this purpose and find that it meets all the requirements. We used secondary ion mass spectrometry to find that 18 nm, heavily B-doped layers remain intact after implantation into the surface polysilicon and annealing at 800 °C for 40 s. Similar samples without the surface polylayer displayed extreme broadening of B profile. Kelvin crossbridge resistors together with 2D device simulations revealed that ρc is an extremely low value of 1.2×10−8 Ω cm2 in as-deposited material. Fabrication of simple 30×30 μm2 mesa isolated HBT devices showed IC to be more than two decades higher in devices with only an in situ As-doped polyemitter compared with devices that incorporated a surface implant into the single crystal portion of the emitter before polysilicon deposition. These results demonstrate that this doped polycrystalline silicon material is an excellent choice for emitter contacts to HBT devices. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116468
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