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Raman Spectroscopy for the Analysis οf Temperature-Dependent Plastic Relaxation οf SiGe Layers

100%

Pezzoli F., Bonera E., Bollani M., Sanguinetti S., Grilli E., Guzzi M., Isella G., Chrastina D., von Känel H.

Acta Physica Polonica A

2009

vol. 116

issue 1

78-80

Novel architectures for electronics and photonics are expected to be developed using the forthcoming Si_{1-x}Ge_{x} technology. However, in Si_{1-x}Ge_{x}-based heterostructures, materials and design issues rely on accurate control of strain and composition of the alloy. The Raman spectroscopy has rapidly emerged as a reliable technique for the quantitative determination of such parameters on a sub-micrometric scale. In this work we present an investigation of the effects of the growth conditions of Si_{1-x}Ge_{x} graded layers on dislocation nucleation and interaction. In particular, we focus on the crucial role the deposition temperature plays in the dislocation kinetics. The analysis of threading dislocation densities is accompanied by a quantitative measurement of the residual strain in Si_{1-x}Ge_{x}/Si heterostructures, carried out by means of the Raman scattering. Our approach is effective in studying the physical mechanism governing dislocation multiplication and the sharp transition from a state of brittleness to a state of ductility within a narrow temperature window.

A Structural Characterization of GaAs MBE Grown on Si Pillars

81%

Frigeri C., Bietti S., Scaccabarozzi A., Bergamaschini R., Falub C., Grillo V., Bollani M., Bonera E., Niedermann P., von Känel H., Sanguinetti S., Miglio L.

Acta Physica Polonica A

2014

vol. 125

issue 4

986-990

Growth on deeply patterned substrates, i.e. on pillars instead of a continuous substrate, is expected to be very promising to get crack free epilayers on wafers without any bowing. We report here on a structural investigation of GaAs MBE deposited on patterned (001) offcut Si, consisting of pillars 8 μm high and 5 to 9 μm wide, to check mostly the behaviour of the threading dislocations. It is found that only very rarely they propagate up to the GaAs top that will serve as active region in devices. Twins were also detected which sometimes reached the topmost part of GaAs. However, as twins have no associated dangling bonds, they should not be electrically active. Rare antiphase boundaries exist at the interface, hence not harmful for device operation.

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2 Acta Physica Polonica A

1 2014

1 2009

2 Bollani M.

2 Bonera E.

2 Sanguinetti S.

2 von Känel H.

1 Bergamaschini R.

1 Bietti S.

1 Chrastina D.

1 Falub C.

1 Frigeri C.

1 Grilli E.

1 Grillo V.

1 Guzzi M.

1 Isella G.

1 Miglio L.

1 Niedermann P.

1 Pezzoli F.

1 Scaccabarozzi A.

Search results

Raman Spectroscopy for the Analysis οf Temperature-Dependent Plastic Relaxation οf SiGe Layers

A Structural Characterization of GaAs MBE Grown on Si Pillars