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1

Influence of Correlated Thermal Vibrations on Temperature Dependence of Surface Peak

100%

Gwizdałła T., Czerbniak J.

Acta Physica Polonica A

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1996

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vol. 89

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issue 1

61-67

EN

The influence of correlation between thermal displacements of atoms in string on the calculated Rutherford backscattering spectra under channelling conditions was studied. This correlation was incorporated into the existing Monte Carlo computer code by means of sampling the displacements from distribution transformed by the variance-covariance matrix. Various methods of implementing the correlation into calculation were used. As a result the deformation of energy spectrum was obtained. The explicit decrease in surface peak due to the correlation was observed. The significance of this effect decreases with increasing temperature. Calculation were performed in a wide region of temperatures, up to the melting point.

2

Effective Ion Charge

100%

Moneta M.

Acta Physica Polonica A

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1996

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vol. 89

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issue 5-6

581-594

EN

The impact parameter dependent energy transfer and random stopping power for ions carrying electrons were determined within the first-order Born approximation. The ion and atom were described by many-electron ground states. The excitations and ionizations of both collision partners were taken into account, but exchange of electrons was neglected. With the Bethe sum rule and closure relation, the random stopping was shown to have the Bethe form. For the Moliere form factors the analytical results were obtained. The effective charge was discussed in the random and channelling conditions. Comparison with some previous calculations was carried out.

3

Thermally Induced Intermixing of InGaAs/GaAs Single Quantum Wells

100%

Kozanecki A., Gillin W., Sealy B.

Acta Physica Polonica A

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1993

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vol. 84

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issue 4

621-624

EN

In this work interdiffusion and strain relaxation in In_{0.2}Ga_{0.8}As/GaAs single quantum wells subjected to rapid thermal annealing have been studied using photoluminescence and Rutherford backscattering of 1.5 MeV He^{+} ions. It has been found that the diffusion coefficient of In atoms in GaAs, evaluated from the photoluminescence spectra for the assumed Gaussian well shapes, agrees within 30% with that obtained using Rutherford backscattering. Channeling angular scans, through the ⟨110⟩ axial direction of the heterostructures indicate that strain relaxation in the intermixed wells is exclusively due to compositional shallowing of the wells.

4

On the Correspondence of the Experimental EEL Spectra with the Electron Structure of Tungsten

80%

Czyżewski J., Krajniak J., Klein S.

Acta Physica Polonica A

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1992

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vol. 81

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issue 1

67-72

EN

In the previous paper [7] we have directly compared the experimental Electron Energy Loss (EEL) spectra with both the theoretical bulk density-of-states (BDOS) and surface density-of-states (SDOS) functions for tungsten. On the base of the ILEED intensity calculations we have estimated to what extend an EEL spectrum measured at some value of the primary electron energy E_{p}, should correspond either to the SDOS or to the BDOS. Also, the angular acceptance of a CMA has been used to separate the EEL spectra measured as a function of E_{p} which corresponded either to the [001] direction or to the [011] in parallel to the studied (001) surface. In the present paper we propose a procedure which combines the Electron Energy Loss Spectra (EELS) simulation method based on Bauer's theory [1,2] and the inelastic low energy diffraction (ILEED). If the standard simulation procedure is applied for tungsten an ambiguity would arise because the DOS function is very anisotropic and varies as a function of both the direction along the surface and the depth considered within several atomic layers. The application of ILEED has supplemented the simulation procedure with the method which identifies both the correspondence of a reciprocal-lattice vector to a measured EEL spectrum and the localization of a studied electron structure with regard to the distance from the surface.

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4 Acta Physica Polonica A

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1 Czerbniak J.

1 Czyżewski J.

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1 Klein S.

1 Kozanecki A.

1 Krajniak J.

1 Moneta M.

1 Sealy B.

Influence of Correlated Thermal Vibrations on Temperature Dependence of Surface Peak

Effective Ion Charge

Thermally Induced Intermixing of InGaAs/GaAs Single Quantum Wells

On the Correspondence of the Experimental EEL Spectra with the Electron Structure of Tungsten