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Free Exciton Luminescence in ZnCdSe Solid Solutions, ZnSe Epitaxial Films and ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} Superlattices

100%

Tenishev L., Permogorov S., Fedorov D., Yakushcheva G., Kuznetsov P.

Acta Physica Polonica A

1996

vol. 90

issue 5

959-964

We studied the luminescence of bulk Zn_{1-x}Cd_{x}Se solid solutions, epitaxial ZnSe films and ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} superlattices at T=2-80 K. The analysis of the bands of exciton radiative annihilation with simultaneous emission of 1 or 2 LO phonons shows that the excitons in the studied samples can be considered as free particles with thermalized distribution of kinetic energies. In ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} superlattices a three-dimensional character of exciton motion was established. The periodic potential of superlattice perturbs the exciton wave vector and induces additional elastic scattering of excitons.

Grain-Subgrain Structure and Vacancy-Type Defects in Submicrocrystalline Nickel at Low Temperature Annealing

86%

Kuznetsov P., Lider A., Bordulev Y., Laptev R., Rakhmatulina T., Korznikov A.

Acta Physica Polonica A

2015

vol. 128

issue 4

714-717

Scanning tunneling microscopy, positron annihilation and X-ray diffraction were applied for the study of annealing of submicrocrystalline nickel prepared by equal channel angular pressing. Several processes were revealed in the structure of submicrocrystalline nickel on different scale levels during annealing in the range Δ T=(20÷360)°C. A decrease of grain nonequiaxiality and further structure refinement were observed with a temperature increase in the range Δ T=(20÷180)°C. Subgrain growth with maximum =60 nm at 120°C occurred on the lower scale level within the same temperature range. Grain growth and microstress decrease in submicrocrystalline nickel observed at T>180°C indicate the beginning of recrystallization. The main positron trap centers were identified in submicrocrystalline nickel within different temperature ranges. In as-prepared samples positrons are trapped at dislocation-type defects and vacancy clusters that can include up to 5 vacancies. At the annealing temperature Δ T=(20÷180)°C positrons are trapped at low-angle boundaries enriched by impurities. Within the range Δ T=(180÷360)°C the dominant trap is dislocations.

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2 Acta Physica Polonica A

1 2015

1 1996

2 Kuznetsov P.

1 Bordulev Y.

1 Fedorov D.

1 Korznikov A.

1 Laptev R.

1 Lider A.

1 Permogorov S.

1 Rakhmatulina T.

1 Tenishev L.

1 Yakushcheva G.

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Free Exciton Luminescence in ZnCdSe Solid Solutions, ZnSe Epitaxial Films and ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} Superlattices

Grain-Subgrain Structure and Vacancy-Type Defects in Submicrocrystalline Nickel at Low Temperature Annealing