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1

Dependence of nonlinear refractive index of ZnSe on Be and Mg content

Derkowska B., Firszt F., Marasek A., Sahraoui B.

Opto-Electronics Review

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2010

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Vol. 18, No. 4

384-387

EN

The values of the nonlinear refractive index n₂ and the two-photon absorption coefficient ß of ternary and quaternary ZnSe-based mixed crystals were extracted from the standard backward degenerate four wave mixing (DFWM) and nonlinear transmission measurements at 532 nm, respectively. Studied crystals were grown by the modified high-pressure Bridgman method. We found that the value of the nonlinear refractive index n2 for Zn0.79Be0.21Se is higher than that for Zn0.80Mg0.20Se. However, the opposite behaviour was found in the case of two-photon absorption coefficient ß for these compounds. We also found that the values of the nonlinear refractive index n2 and the two-photon absorption coefficient ß for Zn0.83Be0.04Mg0.13Se are about five times lower and three times higher than that for Zn0.80Mg0.13Se, respectively. In the case of ternary ZnSe-based crystals we noticed that the value of the nonlinear refractive index n2 decreases with increasing Mg or Be content. However, the value of the two-photon absorption coefficient ß increases with increasing Mg or Be content.

2

Study of the third order nonlinear optical properties of Zn1-xMgxSe and Cd1-xMgxSe crystals

Derkowska B., Firszt F., Sahraoui B., Marasek A., Kujawa M.

Opto-Electronics Review

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2008

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Vol. 16, No. 1

8-11

EN

Third order nonlinear optical susceptibilities χ³ of ternary Zn₁-xMgxSe and Cd₁-xMgxSe crystals have been measured using standard degenerate four-wave mixing (DFWM) method at 532 nm. The nonlinear transmission technique has been applied to check if our crystals exhibit two-photon absorption. The studied Zn₁-xMgxSe and Cd₁-xMgxSe solid solutions were grown from the melt by the modified high-pressure Bridgman method. For both crystals the energy gap increases with increasing Mg content. In the case of Zn₁-xMgxSe, it was found that the value of third order nonlinear optical susceptibility χ³ decreases with increasing Mg content. An explanation of this behaviour results from the dependence of optical nonlinearities on the energy band gap Eg of the studied crystals. In the case of Cd₁₋xMgxSe with low content of Mg, no response was observed for the studied wavelength since the energy gap in such crystals is smaller than the photon energy of the used laser radiation. It was also found that the value of third order nonlinear optical susceptibility χ³ for Cd₀.₇₀Mg₀.₃₃ is higher than for Zn₀.₆₇Mg₀.₃₃Se. This behaviour can be understood if one take into consideration that the free carrier concentration in Cd₁₋xMgxSe samples is about four orders of magnitude higher than that in Zn₁₋x MgxSe ones with comparable Mg content respectively. It is commonly known that when the electric conductivity increases, the values of nonlinear optical properties increase. From the performed measurements one can conclude that the incorporation of Mg as constituent into ZnSe and CdSe crystals leads to a change of the third order nonlinear optical susceptibilities.

3

Photoelectric and photothermal properties of selected II-VI mixed crystals

Firszt F., Łęgowski S., Marasek A., Męczyńska H., Pawlak M., Zakrzewski J.

Opto-Electronics Review

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2004

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Vol. 12, No. 1

161--164

EN

The paper presents investigations of optoelectric and thermal properties of ternary and quaternary II-VI mixed crystals Zn₀.₇Mg₀.₃Se, Zn₀.₈₈Be₀.₁₂Se, Zn₀.₈₃Mg₀.₁₃Be₀.₀₄Se, Zn₀.₈₆Mn₀.₀₈B₀.₀₆Se grown from the melt. The photoluminescence, photoconductivity and photoacoustic amplitude and phase spectra were measured. The energy gap and thermal diffusivity were estimated from photoacoustic spectra. Ionisation energies of defects responsible for observed photoconductivity were determined.

4

Study of Zn1-xMgxSe and Zn1-xBexSe semiconducting crystals by Raman scattering

Szybowicz M., Kozielski M., Firszt F., Łęgowski S., Męczyńska H., Szatkowski J., Paszkowicz W.

Opto-Electronics Review

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1999

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Vol. 7, No. 2

103-106

EN

Wide gap II-VI mixed crystals containing Mg and Be are recently studied extensively for their application in constructing blue-green laser diodes. This work deals with experimental study of optical modes in Zn1-xMgxSe and Zn1-xBexSe semiconductors using Raman scattering method. Measurements have been performed at room and liquid nitrogen temperatures for Zn1-xMgxSe crystals with Mg content in the range 0 < x < 0,34 and for Zn1-xBexSe with Be content in the range 0 < x 0,26. From polarised Raman spectra the longitudinal (LO) and the transverse (TO) optical mode, corresponding to ZnSe- and MgSe - like modes in Zn1-x MgxSe and to ZnSe- and BeSe - like modes in Zn1-xBexSe, were determined. These lattice vibrations can be described by the modified random element isodisplacement (MREI) model.

5

Photoluminescence and structural properties of selected wide-gap II-VI solid solutions.

Firszt F., Łęgowski S., Męczyńska H., Sekulska B., Szatkowski J., Paszkowicz W., Marczak M.

Opto-Electronics Review

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1999

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Vol. 7, No. 2

87-92

EN

This work presents results of investigations of photoluminescence and structural properties of ternary Zn₁-xBexSe, Cd₁-xMgxSe, Zn₁-xMgxSe and quaternary Cd₁-x-yMgxZnySe, Zn₁-x-yBexMgySe, Zn₁-xMgxSe₁-ySy mixed crystals. These crystals were grown from the melt by the high-pressure Bridgman method. Zn₁-xMgxSe and Zn₁-xSrxSe were also obtained by annealing of ZnSe crystals in evacuated quartz ampoules containing Mg or Sr metal. It has been found that admixing of Mg into ZnSe favours the formation of wurtzite Zn₁-xMgxSe while Besphalerite Zn₁-xBexSe structures. Low temperature (40 K) photoluminescence spectra consist of exciton, edge and deep levels emission bands. For most of investigated crystals the emission corresponding to the highest photon energy line in luminescence spectrum is observed up to room temperature.

6

Structure of bulk ZnSe based solid solutions containing Mg and Be

Paszkowicz W., Dłużewski P., Spolnik Z., Godwod K., Domagała J., Firszt F., Sekulska B., Szatkowski J.

Electron Technology

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1998

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Vol. 31, No. 2

208-212

EN

Structural properties, defects and exciton transition energy of bulk Zn₁-xMgxSe, 0 ≤ x ≤ 0.63, and Zn₁-xBexSe, 0 ≤ x ≤ 0.18, crystals are briefly reported. Zn₁-xMgxSe crystallises in the sphalerite strucrure type for low x and in the wurtzite one for hight x, while at x about 0.18, 4H and 8H polytypes may be formed. Zn₁-xBexSe crystallises in the sphalerite type in the studied composition range. An increase of microhardness in Zn0.82Be0.18 by the factor 2.37 in relation to ZnSe is observed.