Lack of Photoemission Evidence for Tailing of Density of States into Energy Gap of Amorphous Si

ABSTRACTWe present a novel family of photodetectors based on hydrogenated amorphous Si/SiC p-i-n-i-p heterostructures. Front p-i-n and rear n-i-p diodes work one as a detector and the other as a load impedance, depending on the polarity of the applied voltage. Due to different absorption at different wavelengths, the devices operate as bias-controlled light detectors in either the blue or the red regions. The energy gap and the thickness of the two intrinsic layers have been optimized to obtain a sharp wavelength selection (centered at 430 and 630 nm) with high rejection-ratios and good quantum efficiencies. The I-V characteristics and the device time response are investigated and simulated by SPICE.

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ENERGY GAP DEPENDENCE ON ANION CONCENTRATION FOR GaxIn1-xAsyP1-y QUATERNARY ALLOY BY RECURSION METHOD

Modern Physics Letters B ◽

10.1142/s0217984904007463 ◽

2004 ◽

Vol 18 (18) ◽

pp. 955-962

Author(s):

MUSA EL-HASAN ◽

REZEK ESTATIEH

Keyword(s):

Density Of States ◽

Energy Gap ◽

Local Density ◽

Tight Binding ◽

Quaternary Alloy ◽

Average Density ◽

Local Density Of States ◽

Recursion Method ◽

Orbital Decomposition ◽

Lattice Matched

Three terminators have been tested, square root terminator, quadreture terminator and linear terminator, it was found that the linear terminator is the best, so it was used in calculating local density of states (LDOS) and it's orbital decomposition, alloy average density of states, and energy gap for different anion concentrations for InP lattice matched alloy. The results were compared with our previous calculations of (LDOS), and results from other methods. Energy gap was compared with experimental measurements. A five orbital sp3s* per atom model was used in the tight-binding representation of the Hamiltonian.

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GAP-LABELING PROPERTIES OF THE ENERGY SPECTRUM FOR TWO-DIMENSIONAL FIBONACCI QUASILATTICES

Modern Physics Letters B ◽

10.1142/s0217984995000073 ◽

1995 ◽

Vol 09 (01) ◽

pp. 55-66

Author(s):

YOUYAN LIU ◽

WICHIT SRITRAKOOL ◽

XIUJUN FU

Keyword(s):

Energy Spectrum ◽

Density Of States ◽

Energy Gap ◽

Fractional Part ◽

Numerical Results ◽

Step Height ◽

Integrated Density Of States ◽

Two Dimensional

We have analytically obtained the occupation probabilities on subbands of the hierarchical energy spectrum and the step heights of the integrated density of states for two-dimensional Fibonacci quasilattices. Based on the above results, the gap-labeling properties of the energy spectrum are found, which claim that the step height is equal to {mτ}, where the braces denote the fractional part, and m is an integer that can be used to label the corresponding energy gap. Numerical results confirm these results very well.

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Determination of Density of Localized States in Amorphous Silicon Alloys From the Low Field Conductance of Thin N-I-N Diodes

MRS Proceedings ◽

10.1557/proc-49-69 ◽

1985 ◽

Vol 49 ◽

Cited By ~ 7

Author(s):

Michael Shur ◽

Michael Hack

Keyword(s):

Temperature Dependence ◽

Amorphous Silicon ◽

Bulk Density ◽

Density Of States ◽

Energy Gap ◽

Localized States ◽

New Technique ◽

Silicon Alloys ◽

Low Field ◽

Density Of Localized States

AbstractWe describe a new technique to determine the bulk density of localized states in the energy gap of amorphous silicon alloys from the temperature dependence of the low field conductance of n-i-n diodes. This new technique allows us to determine the bulk density of states in the centre of a device, and is very straightforward, involving fewer assumptions than other established techniques. Varying the intrinsic layer thickness allows us to measure the,density of states within approximately 400 meV of midgap.We measured the temperature dependence of the low field conductance of an amorphous silicon alloy n-i-n diode with an intrinsic layer thjckness of 0.45 microns and deduced the density of localised states to be 3xlO16cm−3 eV−1 at approximately 0.5 eV below the bottom of the conduction band. We have also considered the high bias region (the space charge limited current regime) and proposed an interpolation formula which describes the current-voltage characteristics of these structures at all biases and agrees well with our computer simulation based on the solution of the complete system of transport equations.

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Temperature dependence of the superconducting energy gap within the Eliashberg theory involving the energy-varying electronic density of states

Physica C Superconductivity ◽

10.1016/0921-4534(95)00227-8 ◽

1995 ◽

Vol 248 (1-2) ◽

pp. 83-91 ◽

Cited By ~ 6

Author(s):

Yasushi Yokoya ◽

Yoshiko Oi Nakamura

Keyword(s):

Temperature Dependence ◽

Density Of States ◽

Energy Gap ◽

Electronic Density ◽

Eliashberg Theory ◽

Electronic Density Of States ◽

Superconducting Energy Gap

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Vibrational Properties of Si Microclusters and Comparison to the Amorphous Material

MRS Proceedings ◽

10.1557/proc-206-79 ◽

1990 ◽

Vol 206 ◽

Author(s):

Joseph L. Feldman ◽

Efthimios Kaxiras

Keyword(s):

Density Of States ◽

Interatomic Potential ◽

Amorphous Material ◽

Vibrational Properties ◽

Dynamical Matrix ◽

Vibrational Density Of States ◽

Remarkable Similarity ◽

Surface Reconstructions ◽

Amorphous Si ◽

Vibrational Density

ABSTRACTThe lattice vibrational properties of two clusters of Si atoms are studied using the Stillinger-Weber phenomenological interatomic potential to calculate the dynamical matrix. The clusters contain 33 and 45 atoms, and their structure was postulated from considerations of surface reconstructions in analogy to crystalline Si surfaces. A remarkable similarity to the vibrational density of states of amorphous Si is demonstrated especially for the 45 atom cluster.

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Paramagnetic impurities in an itinerant antiferromagnet. Theory

Canadian Journal of Physics ◽

10.1139/p69-063 ◽

1969 ◽

Vol 47 (5) ◽

pp. 477-487 ◽

Cited By ~ 22

Author(s):

S. N. Behera ◽

K. S. Viswanathan

Keyword(s):

Density Of States ◽

Energy Gap ◽

Impurity Site ◽

Atom Ratio ◽

Hartree Fock ◽

Paramagnetic Impurities ◽

Spin Dependent Scattering ◽

Experimental Findings ◽

Gap Parameter ◽

Theory And Experiment

The effects of 3-d paramagnetic impurities in an itinerant antiferromagnetic metal are investigated using the Wolff–Clogston model. The changes in the Néel temperature TN, the energy-gap parameter, and the density of states are evaluated in the Hartree–Fock approximation and in the lowest order in the impurity concentration. The results on the changes in TN are compared with the experimental findings on V, Mn, Fe, Co, Ni, Mo, and W impurities in chromium. The agreement between theory and experiment suggests that the changes in TN are essentially due to three mechanisms: (a) the effect due to changes in the electron–atom ratio, (b) the spin-dependent scattering due to paramagnetic impurities, and (c) the changes in the intra-atomic coulomb potential at the impurity site. In the case of Mo and W, the last effect explains the observed decrease in TN in Cr.

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