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Contenido archivado el 2022-12-23

Study of SiGe layers epitaxially grown on Si by Ion sputter deposition

Objetivo

- To study SiGe alloy films epitaxially grown on silicon by ion beam sputter deposition (IBSD);
- To determine the influence of the growth technique on the SiGe films properties, such as stress and roughness;
- To find optimal deposition parameters;
- To determine the thermal stability of the film stress after annealing.
Expected Outcome

- Evaluation of the potentialities of IBSD to grow SiGe films;
- Identification of the defects which lead to compressive strain;
- Strain relaxation in IBSD SiGe films.

Results

- The optimal growth temperature for a Ge-content of 20-25 % is found to be close to 550°C - 625°C.
- IBSD leads to more abrupt interfaces and smoother films than molecular beam epitaxy. This result is related to the energetic bombardment of the growing films.

- The samples grown at low (< 550°C) temperatures reveal point-like defects due to the bombardment of the growing film with high energetic Si and Ge atoms. These defects are parallel to {113} and {001} lattice planes and lead to an additional compressive stress (sigma = -1 GPa) in the films.
- Point-like defects are missing in the layers grown at 700°C. The films are then characterised by the presence of extended dislocations in the bulk of the layer as well as in the SiGe/Si interface and the Si substrate.
- These defects are distributed across the entire SiGe film. This more or less random distribution of defects leads to local fluctuations of the interplane distance. The average magnitude of the fluctuations was derived from high-resolution X-ray diffraction spectra using a novel simulation procedure.
- A detail study of strain relaxation kinetics in IBSD SiGe films clearly demonstrated that the strain relaxation is not a one-step thermally activated process but is governed by different mechanisms with various relaxation times.
- These defects are distributed across the entire SiGe film. This more or less random distribution of defects leads to local fluctuations of the interplane distance. The average magnitude of the fluctuations was derived from high-resolution X-ray diffraction spectra using a novel simulation procedure.

Follow-up

Both groups are continuously co-operating on :
- Electrical properties of Schottky diodes on SiGe films;
- Properties of ternary alloy SiGeC, local order in particular.

This collaboration is supported through an Arc en Ciel program.
The research project integrates a large number of techniques of characterisation :
- Growth mode was studied in situ by Auger electron spectroscopy;
- Topology was studied ex-situ by atomic force microscopy;
- Strain was investigated by X-ray diffraction and Raman spectroscopy;
- Stress was determined from the measurement of the substrate curvature after deposition;
- Composition was determined by secondary ion mass spectroscopy, electron dispersive spectroscopy and Rutherford backscattering spectroscopy;
- Crystal defects were studied by transmission electron microscopy;
- Rapid thermal annealing and conventional annealing were performed under nitrogen or vacuum.

Tema(s)

Data not available

Convocatoria de propuestas

Data not available

Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

UNIVERSITE DE PARIS-SUD XI
Aportación de la UE
Sin datos
Dirección
Université Paris XI - Bètiment 414
91405 ORSAY
Francia

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Coste total
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