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TitleStructural and electrical studies of ultrathin layers with Si0.7Ge0.3 nanocrystals confined in a SiGe/SiO2 superlattice
Author(s)Vieira, E. M. F.
Martín-Sánchez, J.
Rolo, Anabela G.
Parisini, Andrea
Buljan, Maja
Capan, I.
Alves, Eduardo
Barradas, Nuno P.
Conde, Olinda
Bernstorff, Sigrid
Chahboun, A.
Levichev, S.
Gomes, M. J. M.
RF-magnetron sputtering
Raman spectroscopy
MOS structures
Charge trapping
C-V curve
Multi-layer films
Issue date2012
PublisherAIP Publishing
JournalJournal of Applied Physics
Abstract(s)In this work, SiGe/SiO2 multi-layer (ML) films with layer thickness in the range of a few nanometers were successfully fabricated by conventional RF-magnetron sputtering at 350ºC. The influence of the annealing treatment on SiGe nanocrystals (NCs) formation and crystalline properties were investigated by Raman spectroscopy and grazing incidence x-ray diffraction. At the annealing temperature of 800 ºC, where well defined SiGe NCs were observed, a thorough structural investigation of the whole ML structure has been undertaken by Rutherford backscattering spectroscopy, grazing incidence small angle x-ray scattering, high resolution transmission electron microscopy, and annular dark field scanning transmission electron microscopy. Our results show that the onset of local modifications to the ML composition takes place at this temperature for annealing times of the order of a few tens of minutes with the formation of defective regions in the upper portion of the ML structure. Only the very first layers over the Si substrate appear immune to this problem. This finding has been exploited for the fabrication of a defect free metal-oxide-semiconductor structure with a well-defined single layer of SiGe NCs. A memory effect attributed to the presence of the SiGe NCs has been demonstrated by high frequency capacitance-voltage measurements.
DescriptionThe authors would like also to thank José Santos for technical support.
Publisher version
AccessRestricted access (UMinho)
Appears in Collections:CDF - CEP - Artigos/Papers (with refereeing)
CDF - FMNC - Artigos/Papers (with refereeing)

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