454-zheng-jes-1990-2812 - JOURNAL SOLID-STATE-AND OF THE...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
JOURNAL OF" THE ELECTROCHEMICAL SOCIETY SOLID-STATE SCIENCE ---- AND TECHNOLOGY ~ SEPTEMBER L1 D ~""~" , 1990 Oxidation of Single-Crystal Silicon Carbide Part II. Kinetic Model Z. Zheng, R. E. Tressler, and K. E. Spear Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 ABSTRACT The oxidation of single-crystal SiC in dry oxygen (10-3-1 atm and 1200~176 followed parabolic kinetics. The oxy- gen partial pressure dependence of the oxidation rate of the (0001) carbon face decreased with increasing temperature (from 0.6 at 1200~ to 0.3 at 1500~ A kinetic model based on parallel transport of oxidants through the oxide via molecu- lar and ionic oxygen diffusion mechanisms fits the observed oxidation behavior. Both diffusivity and activation energy values for oxidants permeating through the oxide derived from the model using the experimental data are similar to those for molecular oxygen permeating through vitreous SIO2. Ionic oxygen diffusion inward via the lattice presumably via a vacancy mechanism becomes more important when oxidation takes place at higher temperatures and at low oxygen par- tial pressures. Both diffusivity and activation energy values for the ionic oxidant diffusion derived from the model using the experimental data are similar to those values for the diffusion of oxygen through silica reported in the literature. In a companion paper we have concluded that the oxida- tion of single-crystal SiC in dry oxygen (10-3-1 arm and 1200~176 followed parabolic kinetics (1). Two different apparent activation energies were calculated for oxidation of the (0001) C faces of SiC (around 120 kJ/mol below 1350~ and 260 kJ/mol above 1350~ Two regimes were not apparent for oxidation of the (0001) Si faces, and appar- ent activation energies lie between 223-298 kJ/mol. Double oxidation experiments using 160~ and 1802 indicated that the process is dominated by the transport of molecular ox- ygen at lower temperatures with a substantial contribution due to diffusion of ionic oxygen at higher temperatures. Epitaxially grown SiI3C films on alpha-Si~2C substrates via CVD were used to study carbon transport behavior during oxidation of SiC. SIMS analyses showed that carbon can transport quickly through the oxide layer, which elimi- nates the possibility that transport of carbonaceous spe- cies is rate controlling in the oxidation of SiC. The oxida- tion mechanisms of SiC were hypothesized to be parallel transport of oxidants through the growing oxide layer via molecular oxygen and ionic oxygen diffusion mech- anisms. The change of activation energies in lower and higher oxidation temperature regimes listed above agrees with other observations reported in the literature (2-4) with the reported activation energy values increasing from around 120 kJ/mol below 1400~ to around 250-500 kJ/mol above this temperature. The activation energy values around 120 kJ/mol in the lower temperature range are very similar to the activation energy values reported for the oxidation of silicon (5), which corresponds to the activation energy for
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern