absorption emission and gain in silicon nanostructures elena degoli roberto guerra federico iori rita magri ivan marri and stefano ossicini
Stimulated Emission and Optical Gain in Semiconductors
... gives a sharp gain (absorption) edge This is because band tails exist and they contribute to the gain (absorption) With increasing carrier density, the band-filling effect shifts the gain peak towards ... band Figure 3.6 Matrix element of the interband transition in GaAs dependent upon energy (the SME) 3.4 GAIN SPECTRUM AND GAIN FACTOR As we saw above, in the direct-transition model the gain and ... calculation of the gain factor g ¼ À and the spontaneous emission using Eqs (3.21) and (3.23), are outlined The results on the gain and spontaneous emission will then be given in the following sections...
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Phonon assisted tunneling process in amorphous silicon nanostructures and gaas nanowires
... density and W is the rate of tunneling Some tunneling theories accounting the interaction of electrons with phonons are known [5,6], in which the tunneling is temperature-dependent process In the ... conduction band of semiconductor due to the phononassisted tunneling The electron population in the traps is assumed to be independent of bias voltage due to the continuous filling the traps in the interface ... being 70 nm Very similar temperature-dependent I–V data have been obtained by Schricker et al for GaAs nanowires [9] The I–V curves became increasingly nonlinear with decreasing temperature and...
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Effects of simultaneous doping with boron and phosphorous on the structural, electronic and optical properties of silicon nanostructures
... effects of size and shape of Si-nc on the incorporation of group-III (B and Al), group-IV (C and Ge) and group-V (N and P) impurities Single-doping has been investigated both in spherical and faceted-like ... band edge are more intense Codoped silicon nanowires Among one-dimensional semiconducting nanostructures, silicon nanowires (Si-nw) have attracted in the last years an increasing interest since ... distances and in different combinations Besides also doped Si nanowires have been investigated We show, in all systems, that compensated codoping ARTICLE IN PRESS 946 F Iori, S Ossicini / Physica...
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Interplay between phonon confinement effect and anharmonicity in silicon nanowires
... substantial broadening, as evident from a series of Stokes and anti-Stokes Raman spectra taken with laser powers ranging from 10 to 500 mW The softening and broadening are large, up to 30 and 20 cmÀ1, ... laser line power densities anti-Stokes Results and discussion Fig shows typical Raman spectra taken from silicon nanowires A dramatic change in the spectra is observed for the moderate increase in ... be also seen in Figs and that the intensity ratio between the Stokes and antiStokes part of the spectrum decreases as the laser power increases This implies that a dramatic change in the local...
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Raman spectroscopy and field electron emission properties of aligned silicon nanowire arrays
... plane of silicon There is a thin amorphous layer sheathing the crystalline core of the SiNW (bottom right inset in Fig 3), which is identified to be amorphous silicon oxide (SiOx) resulting from ... relaxed ðqa0Þ and Fig TEM image of an individual SiNW with the corresponding SAED pattern (top left) in the inset The bottom right inset shows an HRTEM image of a SiNW ARTICLE IN PRESS 172 C ... broadening The inset shows the signals from bulk c-Si and SiNWs Raman-active modes will not be limited to being at the center of the Brillouin zone (G point) The smaller the crystalline grain, the...
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High-Tech Start-Ups and Industry Dynamics in Silicon Valley potx
... for “moving inside” Silicon Valley, which is not a major concern of our study Death Merger and acquisition Moving inside Moving out Moving in Growth Birth Figure 1.2—Industry Dynamics in Silicon ... Relocating Into Silicon Valley, 1990–2001 4.5 Top Ten Origin Cities for Establishments Relocating Into Silicon Valley, 1990–2001 4.6 High-Tech Establishments Relocating Into and Out of Silicon ... examining Silicon Valley’s high-tech economy in a dynamic context Using two unique longitudinal databases, we investigate firm formation, growth, mortality, and migration in Silicon Valley during...
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Báo cáo khoa học: Benzo[a]pyrene impairs b-adrenergic stimulation of adipose tissue lipolysis and causes weight gain in mice A novel molecular mechanism of toxicity for a common food pollutant doc
... by low doses of norepinephrine exerted a significant inhibition on lipoysis (Fig 1C) The initial step involved in the epinephrine ⁄ norepinephrine-induced lipolytic cascade includes activation ... B[a]P-induced weight gain remain speculative We know, however, that this increase in body weight was not due to an increase in food intake despite a significant decrease in leptin ⁄ weight ratio Indeed, ... lgÆkg)1 epinephrine (d) or saline (s), or (B) 0.5 mgÆkg)1 B[a]P for the indicated times prior to receiving injections of either saline or 0.25 mgÆkg)1 epinephrine Forty-five minutes after injection...
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fowler-nordheim field emission effects in semiconductor nanostructures
... splitting of the two-spin states by the spin–orbit coupling and the crystalline field has been taken into account Section 1.2.3 contains the investigation of the FNFE from QWs of II–VI compounds In ... regarding it and to satisfy his desire, myself with the prominent members of my research team wrote the Einstein Relation in Compound Semiconductors and Their Nanostructures, Springer Series in Materials ... the main driving force since 1985 before his demise with respect to our scripting the new series in band structure-dependent properties of nanoscale materials He strongly in uenced me regarding...
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Báo cáo hóa học: " Effect of annealing treatments on photoluminescence and charge storage mechanism in silicon-rich SiNx:H films" docx
... state luminescence/band-tail luminescence, and luminescence from Si nanodots/clusters In this investigation, efforts have been made to minimize Si/SiN x interface luminescence with the introduction ... subjected to annealing at 1100°C in N2, and subsequently in forming gas (10% H + 90% N ) The PL peak intensity increases about 28% due to this additional forming gas annealing step, indicating passivation ... Electroluminescence studies in silicon dioxide films containing tiny silicon islands J Appl Phys 1984, 56:401 Gritsenko VA: Structure and Electronic Properties of Amorphous Insulators in Silicon MIS Structures...
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Báo cáo hóa học: " Rapid thermal annealing and crystallization mechanisms study of silicon nanocrystal in silicon carbide matrix" doc
... calculated by this formula and are indicated and compared in Figure In both RTA and furnace annealing samples, we can see that when Si concentration increases, Si grain size which is calculated ... stoichiometric SiC film, indicating that SiC film does not crystallize under 1,100°C annealing condition itself due to insufficient kinetic energy [13] That both Si and SiC-NC appear in silicon- rich carbide ... s in the same temperature range and much shorter annealing time of A detailed temperature ramping profile is listed in Table The structural properties including the nanocrystal size, shape, and...
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Báo cáo hóa học: " On the Morphology, Structure and Field Emission Properties of Silver-Tetracyanoquinodimethane Nanostructures" pptx
... can be obtained by desorbing by applying the field for long time It can be reduced that the defects (adsorbate) in the body of emitters result in the emission current and then the nonlinear F–N ... 38.52 and 44.60 indexing for Ag(111) and (200), i.e., showing the same switching effect from single Ag-TCNQ nanowire After the applied field reaches the value of turn-on field, the switching happens, ... that the emission area in this high field region not changed, and the stability of field emission is high The slopes and intercedes of these plots in the high field region are the same, showing the...
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Báo cáo hóa học: " Size-dependent Fano Interaction in the Laser-etched Silicon Nanostructures" docx
... appreciable heating Increase in the asymmetry on increasing excitation laser power density is due to Fano interaction between electronic Raman scattering involving photo-excited electrons within electronic ... 3.1 and FWHM of 14 cm-1 in Fig 2b Figure 2b shows that asymmetry, red shift, and FWHM in Raman line-shape increase by the increasing excitation laser power density Changes in the Raman line-shape ... m-1) in Fig 2a The Raman line-shape has asymmetry ratio of 2.8 with FWHM of 12.5 cm-1 in Fig 2a Asymmetry and broadening in Raman line-shape is attributed to the quantum confinement of phonons in...
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Báo cáo hóa học: " Whispering gallery modes in photoluminescence and Raman spectra of a spherical microcavity with CdTe quantum dots: anti-Stokes emission and interference effects" ppt
... Results and discussion The optical spectra of colloidal CdTe QDs in water are presented in Fig 1, demonstrating the high optical quality by the pronounced peak in absorption and a single band edge ... spectral region Gaining a better insight into these experimental findings, we have studied spectra of CdTe/PS microspheres using low intensity non-resonance excitation by a He–Ne laser In that case, ... adjacent TE and TM modes) again in agreement with measured modes separation (Fig 3a) Periodicities of 0.44 and 0.33 nm, obtained from the Fourier analysis, are indicative of the TE and TM modes...
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Báo cáo y học: "Positive End-Expiratory Pressure may alter breathing cardiovascular variability and baroreflex gain in " ppt
... line) between immune and central nervous system [51]: during an injury or infection, brainstem centers receive sensory inputs from the immune system through humoral (circulating cytokines) and ... the administration of epinephrine or norepinephrine in healthy subjects has failed to demonstrate a change in baroreflex gain or RR variability [54] Lastly, oxygenation status might also be involved, ... [53] In septic shock, baroreflex gain and low-frequency/high-frequency ratio of RR variability were correlated with plasma norepinephrine levels [1] These findings suggest a direct effect of administered...
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Growth and characterization of germanium and silicon nanostructures
... nanostructures are gaining increasing popularity from the industry and transistor devices based on these nanostructures are promising candidates for new manufacturable information processing technologies ... information and signal processing This will likely require a revolutionary means of physically representing, processing, storing and transporting of information via new materials, processes and ... applications in optoelectronics, memory and sensors.20-22 Introduction and Motivation 1.3 Challenges and Opportunities in Syntheses of Si and Ge Nanostructures Despite the fact that Si and Ge nanostructures...
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Theoretical study of elementary processes in silicon germanium epitaxial growth on SI(100) and SI1 xGEx (100) surfaces
... commonly used silicon in semiconductor industry In this work several molecular processes involving in silicon and silicon- germanium epitaxial growth on Si(100) and Si1-xGex(100) surface are investigated ... high-volume silicon- based manufacturing processes By introducing germanium into silicon wafers at the atomic scale, engineers can boost performance while retaining the many advantages of silicon In 2006, ... (c) transition state 12 Introduction 1.1 Silicon and germanium in semiconductor 1.1.1 Silicon and silicon- germanium devices Silicon, the second richest element existing in common stone, has attracted...
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BORON AND PHOSPHORUS DIFFUSION IN SILICON INTERSTITIAL, VACANCY AND COMBINATION MECHANISMS
... presence of silicon self-interstitials, the impurity interstitial may the knock a silicon lattice atom into a self-interstitial position (Fig.1) Fig Vacancy, interstitial and combination machanisms ... pre-exponential, D0 , and diffusion coefficient, D, of B and P in silicon at zero pressure We also compare the calculated results for diffusion of B and P in silicon with the experimental data and the different ... 4.21 Using the experiment data for Si and impurities B and P (Table and Table2), and our theory in Section 2, we the obtain the values of activation energies Q, pre-exponential factor D0 of B and...
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BORON AND PHOSPHORUS DIFFUSION IN SILICON PRESSURE DEPENDENCE
... A) 3.79 4.21 BORON AND PHOSPHORUS DIFFUSION IN SILICON 157 Using the potential parameters for Si and impurities B and P (Tables and 2), and our theory in Section II, we obtain the values of the ... saddle point in its migration path In interpreting atomistic calculations and experiments in the past, the assumption has been made almost universally that, V m , is negligible [10] In the present ... the activation volume, V ∗ , and the diffusion coefficient, D, of B and P atoms in silicon via an interstitialcy mechanism The SMM results are summarized in Tables and The SMM calculated results...
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Chip formation, acoustic emission and surface white layers in hard machining
... sources of AE in metal cutting, one would expect a monotonic increase in AERMSwith depth of cut Clearly, the increasing depth of cut results in an increase in the volume of material undergoing plastic ... formation of folds Noting that the lamella to fold transition occurs with increases in work material hardness and/ or increases in cutting speed and undeformed chip thickness, and that as each of ... pileup and/ or strain incompatibility at carbide or inclusion boundaries In contrast to this fracture mechanism, Ramalingam and Black [I61 and Black [14], [I71 proposed a localised thermal softening...
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Volatile organic compound emission and other trace gases from selected animal buildings ppt
... pushed out once to twice a week Feeding times during sampling were between 7:30 and 8:30 in the morning and between 13:00 and 13:30 in the afternoon Measurements in the sheep shed (dimensions 23 m ... determine the ventilation rate indirectly Though SF6 has unwanted long-term climatic effects, finding a well mixed and inert tracer in the animal building itself is challenging, further limiting ... mixing ratios for these gases including the maximum and minimum values attained in both sheds Figure depicts two days of the week long campaign in the sheep shed with the upper panel showing...
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