Phase separation in SiGe nanocrystals embedded in SiO2 matrix during high temperature annealing

Mogaddam, N. A. P.
Alagoz, A. S.
Yerci, Selçuk
Turan, Raşit
Finstad, T. G.
SiGe nanocrystals have been formed in SiO2 matrix by cosputtering Si, Ge, and SiO2 independently on Si substrate. Effects of the annealing time and temperature on structural and compositional properties are studied by transmission electron microscopy, x-ray diffraction (XRD), and Raman spectroscopy measurements. It is observed that Ge-rich Si(1-x)Gex nanocrystals do not hold their compositional uniformity when annealed at high temperatures for enough long time. A segregation process leading to separation of Ge and Si atoms from each other takes place. This process has been evidenced by a double peak formation in the XRD and Raman spectra. We attributed this phase separation to the differences in atomic size, surface energy, and surface diffusion disparity between Si and Ge atoms leading to the formation of nonhomogenous structure consist of a Si-rich SiGe core covered by a Ge-rich SiGe shell. This experimental observation is consistent with the result of reported theoretical and simulation methods.


Electrochemical preparation and characterization of carbon fiber reinforced poly (dimethyl siloxane)/polythiophene composites: electrical, thermal and mechanical properties
Sankir, M; Kucukyavuz, S; Kucukyavuz, Z (Elsevier BV, 2002-05-10)
A series of polydimethylsiloxane (PDMS)/polythiophene (Pth)/carbon fiber (CF) composites was synthesized by electrochemical polymerization using tetrabutylammoniumtetrafluoroborate (TBAFB) as supporting electrolyte and acetonitrile as solvent. Composites were characterized by TGA, SEM, and mechanical tests and conductivity measurements. Conductivities of composites were in the range of 25 S/cm. SEM studies show that CF were coated by PDMS/Pth matrix and well oriented in the matrix. In mechanical tests it ha...
JELINEK, R; Özkar, Saim; PASTORE, HO; MALEK, A; OZIN, GA (American Chemical Society (ACS), 1993-01-01)
Na-23 double-rotation NMR (DOR) provides site-specific structural and dynamical information on guest-host interactions within sodium zeolite Y pores. Quantitative adsorption of H2O, PMe3, and Mo(CO)6 guests affects both the positions and line shapes of the N-23 resonances from specific extraframework Na+ sites. The evolution of the Na-23 DOR spectra with the progressive introduction of guest molecules allows one to probe direct ''solvation'' effects involving the Na+ cations in the larger supercages, as wel...
Chemical Interactions of Nano Islandic Graphene Grown on Titanium Dioxide Substrates by Chemical Vapor Deposition
Karamat, S.; Khalique, U.; Usman, Arslan; Javaid, Asad; Oral, Ahmet (2022-03-01)
In this work, direct growth of graphene is carried out on TiO2 (110) substrates by chemical vapor deposition. For few device applications, it is convenient to grow graphene directly on the dielectric substrates rather than metal foil to minimize transfer and surface interface defects. Raman spectrum support graphene growth on TiO2 substrate by exhibiting D and G peaks. Graphene covered the whole TiO2 substrate with few areas where higher growth of carbon atoms occurs. The contrast of SEM images clearly show...
Intensity dependent time-resolved photoluminescence studies of GaN/AlGaN multiple quantum wells of varying well width on laterally overgrown a-plane and planar c-plane GaN
Garrett, GA; Shen, H; Wraback, M; İmer, Muhsine Bilge; Haskell, B; Speck, JS; Keller, S; Nakamura, S; DenBaars, SP (Wiley, 2005-04-01)
GaN/AlGaN multiple quantum wells (MQWs) of varying well width grown on planar c-plane GaN and a-plane GaN templates fabricated by lateral epitaxial overgrowth (LEO) have been studied by subpicosecond photoluminescence (PL) downconversion and time-correlated single photon counting as a function of pump intensity. Although slower room temperature decays at higher carrier density are observed in both a-plane LEO and c-plane MQWs with 3 nm well width, this behavior is attributed to suppression of electric field...
Conduction mechanism in H-type polysiloxane-polypyrrole block copolymers
BOZKURT, AYHAN; Parlak, Mehmet; Ercelebi, C; Toppare, Levent Kamil (Wiley, 2002-07-05)
Conducting polymers of polysiloxane-polypyrrole were Synthesized by electropolymerization of the pyrrole monomer through pyrrole moieties in N-pyrrole-terminated polysiloxanes. Sodium paratoluene sulfonate was used as the electrolyte. Scanning electron microscopy (SEM) was used to determine the surface morphology of the films. The room-temperature conductivity values of the films were found to be in the range of 1.9-4.4 x 10(-4) (Omega cm)(-1), depending on the supporting electrolyte concentration. The temp...
Citation Formats
N. A. P. Mogaddam, A. S. Alagoz, S. Yerci, R. Turan, S. FOSS, and T. G. Finstad, “Phase separation in SiGe nanocrystals embedded in SiO2 matrix during high temperature annealing,” JOURNAL OF APPLIED PHYSICS, pp. 0–0, 2008, Accessed: 00, 2020. [Online]. Available: