Intrinsic Optical Absorption in Germanium

The absorption constant of germanium beyond the first direct absorption edge has been determined up to energies of 2.5 eV by transmission measurements on very thin samples prepared from bulk single crystals. The results are discussed in terms of recent band structure calculations and previous reflection measurements. At low temperatures the observed structure gives evidence for exciton formation connected with direct transitions at a saddle point in the energy difference between conduction and valence bands.

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Energetics of C11b, C40, C54, and C49 structures in transition-metal disilicides

Journal of Materials Research ◽

10.1557/jmr.1991.1512 ◽

1991 ◽

Vol 6 (7) ◽

pp. 1512-1517 ◽

Cited By ~ 33

Author(s):

A.E. Carlsson ◽

P.J. Meschter

Keyword(s):

Transition Metal ◽

Spherical Wave ◽

Energy Difference ◽

Group Iv ◽

Computational Method ◽

Electronic Density ◽

Band Structure Calculations ◽

Atomic Coordination ◽

Metal Aluminides ◽

Structure Calculations

The relative energies of the related C11b, C40, and C54 crystal structures of group IV–VII transition-metal disilicides are obtained by ab initio self-consistent band-structure calculations using the augmented-spherical-wave (ASW) method. The structural energy differences among these three structures correlate strongly with d-band filling, with C40 being stabilized relative to C54 and C11b relative to C40 as the transition-metal d-electron count increases. The C40/C11b energy difference is <0.05 eV/atom only for CrSi2 and MoSi2. Relative C11b/C40/C54 energies are similar in magnitude to those obtained in previous studies of L12/D022/D023 competition in transition-metal aluminides.1,2 Calculations of the C49/C54 energetic competition are inaccurate; the differences in atomic coordination in these two structures are probably too large for the computational method to handle accurately. The total-energy results are interpreted by a detailed analysis of the electronic density-of-states (DOS) distributions. The stable structures do not correlate as strongly with DOS effects in the vicinity of the Fermi level as in the aluminides.

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Fermi surface of the skutterudite CoSb3 : Quantum oscillations and band-structure calculations

Physical Review B ◽

10.1103/physrevb.103.085133 ◽

2021 ◽

Vol 103 (8) ◽

Author(s):

M. Naumann ◽

P. Mokhtari ◽

Z. Medvecka ◽

F. Arnold ◽

M. Pillaca ◽

...

Keyword(s):

Band Structure ◽

Fermi Surface ◽

Quantum Oscillations ◽

Band Structure Calculations ◽

Structure Calculations

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The Highly Uniform Photoresponsivity from Visible to Near IR Light in Sb2Te3 Flakes

Sensors ◽

10.3390/s21041535 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1535

Author(s):

Shiu-Ming Huang ◽

Jai-Lung Hung ◽

Mitch Chou ◽

Chi-Yang Chen ◽

Fang-Chen Liu ◽

...

Keyword(s):

Band Structure ◽

Energy Difference ◽

Experimental Result ◽

Light Illumination ◽

Near Ir ◽

State Band ◽

Valence Bands ◽

Low Dimensional ◽

Low Dimensional Materials ◽

Ir Light

Broadband photosensors have been widely studied in various kinds of materials. Experimental results have revealed strong wavelength-dependent photoresponses in all previous reports. This limits the potential application of broadband photosensors. Therefore, finding a wavelength-insensitive photosensor is imperative in this application. Photocurrent measurements were performed in Sb2Te3 flakes at various wavelengths ranging from visible to near IR light. The measured photocurrent change was insensitive to wavelengths from 300 to 1000 nm. The observed wavelength response deviation was lower than that in all previous reports. Our results show that the corresponding energies of these photocurrent peaks are consistent with the energy difference of the density of state peaks between conduction and valence bands. This suggests that the observed photocurrent originates from these band structure peak transitions under light illumination. Contrary to the most common explanation that observed broadband photocurrent carrier is mainly from the surface state in low-dimensional materials, our experimental result suggests that bulk state band structure is the main source of the observed photocurrent and dominates the broadband photocurrent.

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