Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 5: Quantum Dots and Wires: Preparation and Characterization I

HL 5.5: Vortrag

Montag, 26. März 2012, 10:30–10:45, EW 202

Thermodynamic theory of the phase separation in nonstoichiometric silicon oxide films — •Andrey Sarikov¹ and Magrit Zacharias² — ¹V. Lashkarev Institute of Semiconductor Physics NAS Ukraine, Kiev, Ukraine — ²IMTEK, University of Freiburg, Freiburg im Breisgau, Germany

Nonstoichiometric silicon oxide films (SiOx, x < 2) are perspective for optoelectronic applications due to the temperature stimulated phase separation in them and the formation of amorphous or crystalline Si nanoinclusions capable of light emission, in the silicon oxide matrix.

In this work, a thermodynamic theory of the phase separation in nonstoichiometric silicon oxide films is proposed. The expressions for the free energy of nonstoichiometric silicon oxide and silicon oxide with amorphous and crystalline Si nanoinclusions are derived. The free energy of amorphous Si / Si oxide and crystalline Si / Si oxide systems as a function of the relative concentration of separated silicon, the initial silicon oxide stoichiometry, and the temperature is studied. By the free energy minimization, the equilibrium stoichiometries of silicon oxide and the solubilities of Si in SiO2 in contact with amorphous and crystalline silicon are determined. An especial attention is given to the strain appearing as a result of phase separation. The account of strain contribution to the free energy of Si / Si oxide systems enables a comprehensive description of the dependence of the equilibrium stoichiometry of phase separated silicon oxide films on the initial silicon oxide composition and the temperature.