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| 2. |
- Bukaluk, A., et al.
(författare)
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Auger electron spectroscopy, ellipsometry and photoluminescence investigations of Zn1-XBeXSe alloys
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 175-176, s. 531-537
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, properties of the Zn1-XBeXSe crystals grown from the melt by the high-pressure Bridgman method are reported. Spectroscopic ellipsometry has been used for determination of the complex dielectric function of Zn1-XBeXSe. On the basis of the photon energy dependence of the dielectric function, the energy gaps of alloys containing different beryllium concentrations have been evaluated. Measurements of the photoluminescence (PL) spectra allowed to find the excitonic gap in the investigated alloys. Auger electron spectroscopy (AES) with simultaneous argon ion sputtering has been used for determination of surface composition. AES investigations allowed to make predictions concerning distribution of particular elements in the samples. © 2001 Elsevier Science B.V.
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| 3. |
- Wronkowska, A.A., et al.
(författare)
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Characterisation of Cd1-xMgxSe solid solutions by spectroscopic ellipsometry
- 2001
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 63:1-2, s. 233-239
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Optical properties of bulk Cd1-xMgxSe mixed crystals, grown from a CdSe, Mg, and Se melt by the Bridgman method, are presented. The alloys have a wurtzite type structure in the investigated range of composition, i.e. for 0 = x = 0.4. Measurements of the complex pseudo-dielectric function, = + ie2(?)>, were performed at room temperature in the photon energy range of 1.25-4.5 eV, using a computer-controlled variable angle of incidence ellipsometer. The spectral dependence of the effective refractive index and the absorption coefficient were also derived. The structure observed in the dielectric functions, attributed to the interband transitions E0, E0 + ?0 and E1, have been analysed by fitting the and d2/d?2 spectra to the damped harmonic oscillator and critical-point line shapes, respectively. For all critical points, the energy increases with increasing Mg concentration. The ellipsometric results of a fundamental band-gap shift due to Mg content are compared with the rate of increase of the excitonic energy, derived from photoluminescence spectra. © 2001 Elsevier Science Ltd.
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| 5. |
- Wronkowska, A.A., et al.
(författare)
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Investigations of Cd1-xMnxTe crystals by means of ellipsometry and Auger electron spectroscopy
- 2003
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 212-213:SPEC., s. 110-115
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cd1-xMnxTe crystals, obtained by the high-pressure Bridgman method for x = 0, 0.27, 0.49, 0.67 and 0.8, were investigated. Crystal composition was determined by electron microprobe analysis. For an Mn content lower than 0.7, a single phase of pure zinc blend structure was found. In Cd0.2Mn0.8Te samples a two-phase structure was revealed. Auger electron spectroscopy (AES) was used to determine the composition of the crystal surfaces. AES depth profiles obtained by argon sputtering and AES analysis allowed to find the distribution of Cd, Mn and Te inside the sub-surface region. Spectroscopic ellipsometry was applied to determine the complex dielectric function e of the samples. Ellipsometric measurements were performed at room temperature in the photon energy range 0.75-6.5 eV. The spectral dependence of e was used to find the energy gaps Eg of the alloys with different Mn content. Ellipsometric data were correlated with the compositional results obtained from the electron microprobe and AES depth profile investigations. A linear increase of energy gaps with increasing x was observed for chemically homogeneous CdMnTe crystals. © 2003 Elsevier Science B.V. All rights reserved.
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| 6. |
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| 7. |
- Wronkowska, A.A., et al.
(författare)
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Lattice absorption of Be-containing semiconductor alloys determined by spectroscopic ellipsometry
- 2008
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Ingår i: Physica Status Solidi (a) applications and materials science. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 205:4, s. 849-853
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Tidskriftsartikel (refereegranskat)abstract
- Lattice absorption of Zn1–x –yBex Mgy Se and Cd1–x –yBex Zny Se mixed crystals grown by a high pressure Bridgman method has been investigated by infrared spectroscopic ellipsometry in the wave number range from 230 cm–1 to 5000 cm–1. Ellipsometric spectra of Cd1–x –yBex Zny Se crystals display features in the spectral range 350–550 cm–1 associated with BeSe-type phonon modes. In the optical spectra of Zn1–x –yBex Mgy Se crystals both BeSe-type and MgSe-type lattice absorption bands are detected. The MgSe-like modes are located at approximately 300 cm–1. The frequencies and oscillator strengths of optical phonon modes depend strongly on the alloy composition
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| 8. |
- Wronkowska, A A, et al.
(författare)
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Optical spectra of Zn1-xBexTe mixed crystals determined by IR-VIS-UV ellipsometry and photoluminescence measurements
- 2011
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Ingår i: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. - 0040-6090. ; 519:9, s. 2795-2800
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Tidskriftsartikel (refereegranskat)abstract
- Spectroscopic ellipsometry in the photon energy range from 0.04 eV to 6.50 eV is used for investigation of the optical response of Zn1-xBxTe crystals grown by a high-pressure Bridgman method in the composition range x andlt;= 0.12. Infrared spectra display absorption bands centred between 411 cm(-1) and 420 cm(-1) associated with BeTe-type optical phonon modes. The positions of the transverse-optical and longitudinal-optical phonon modes have been found by modelling the line shape of the complex dielectric functions, (epsilon) over tilde and Im(-(epsilon) over tilde (-1)), using a classical damped Lorentzian oscillator approach. Ellipsometric measurements in the VIS-UV range allow determination of the fundamental energy-gap (E-0) and the higher threshold energies (E-1, E-1 + Delta(1), E-2) originating from the band edge and spin-orbit splitting critical points. We have found that the Be content x = 0.12 causes an increase of the fundamental energy gap about 0.15 eV at room temperature when compared to the E-0 = 2.23 eV of ZnTe crystal at the same temperature. Photoluminescence spectra were measured in the temperature range from 30 K to room temperature. Luminescence at temperature Tandgt;200 K is very weak. The peak positions of the exciton emission lines agree well with the E-0 band-gaps derived from ellipsometric data if corrected for their temperature dependence.
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| 9. |
- Wronkowska, A.A., et al.
(författare)
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Spectroscopic ellipsometry and photoluminescence investigation of Zn1-x-yBexMgySe and Cd1-x-yBexZnySe Crystals
- 2008
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 205:4, s. 854-858
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Tidskriftsartikel (refereegranskat)abstract
- Optical and luminescence properties of the Bridgman-grown Cd1–x –yBex Zny Se and Zn1–x –yBex Mgy Se crystals are reported. Spectroscopic ellipsometry was employed for determination of spectral dependence of the complex dielectric function (E) in the photon energy range 0.75–6.5 eV. Below the absorption edge the refractive indices n (E) of the alloys were modelled using a Sellmeier-type relation. The excitonic band-gap energies were estimated from the ellipsometric and photoluminescence measurements. Compositional effects in the ellipsometric and photoluminescence spectra are discussed.
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