Effect of the surface state on the fine structure and fundamental absorption edge of CdS single crystals

The optical properties of single crystals of the hexagonal manganites RMnO3 (R = Ho, Tm, Yb) have been investigated by spectroscopic ellipsometry in the spectral range 0.6-5.0 eV. The measurements show a strong anisotropy of the diagonal elements of the dielectric tensor. It has been demonstrated that the optical absorption edge for the polarization Ec was determined by the intense band of O(2p)Mn (3d) transition centered near 1.6 eV, whereas this band for the polarization Ec was strongly suppressed and shifted toward higher energies by 0.15-0.20 eV. The spectral dependences of the ε1(E) and ε2(E) for HoMnO3, TmMnO3 and YbMnO3 single crystals were qualitatively similar. The broad absorption band at E<1.0 eV clearly appears at the energies below the fundamental absorption edge of all of study compounds. It is possible, the origin of the near-infrared ε2(E) absorption is associated with 4f-4f transitions of R3+ ions.

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Features of the fine structure of the fundamental absorption edge in low-doped semiconductor quantum wells with allowance for the Coulomb gap

Journal of Contemporary Physics (Armenian Academy of Sciences) ◽

10.3103/s1068337209020091 ◽

2009 ◽

Vol 44 (2) ◽

pp. 99-103

Author(s):

S. L. Harutyunyan

Keyword(s):

Fine Structure ◽

Quantum Wells ◽

Absorption Edge ◽

Fundamental Absorption Edge ◽

Coulomb Gap ◽

Semiconductor Quantum Wells

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Кристаллическая структура и ширина запрещенной зоны твердых растворов (MnIn-=SUB=-2-=/SUB=-S-=SUB=-4-=/SUB=-)-=SUB=-1-x-=/SUB=-·(AgIn-=SUB=-5-=/SUB=-S-=SUB=-8-=/SUB=-)-=SUB=-x-=/SUB=-

Физика и техника полупроводников ◽

10.21883/ftp.2018.08.46227.8643 ◽

2018 ◽

Vol 52 (8) ◽

pp. 958

Author(s):

И.В. Боднарь ◽

Чан Бинь Тхан

Keyword(s):

Crystal Structure ◽

Band Gap ◽

Single Crystals ◽

Absorption Edge ◽

Entire Range ◽

Spinel Structure ◽

Cell Parameter ◽

Fundamental Absorption Edge ◽

Composition Parameter ◽

First Time

AbstractThe (MnIn_2S_4)_1– x • (AgIn_5S_8)_ x alloy single crystals are grown for the first time by the Bridgman method in the entire range of component concentrations. The composition of the single crystals and their crystal structure are determined. It is shown that the alloy crystallizes in the cubic spinel structure. The unit-cell parameter of the single crystals ( a ) is calculated, and its dependence on the composition parameter ( x ) is determined. It is established that the parameter a linearly varies with x . From the transmittance spectra in the region of the fundamental absorption edge, the band gap ( E _ g ) of the MnIn_2S_4 and AgIn_5S_8 compounds and (MnIn_2S_4)_1– x • (AgIn_5S_8)_ x alloys is determined, and the dependence of Eg on the parameter x is constructed. It is found that the band gap E _ g nonlinearly varies with x and has a maximum at x = 0.6.

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