We have investigated photoluminescence (PL) from Si-based anodic porous alumina films formed by real-time controlled anodization
of electron-beam evaporated Al films. As-anodized samples show three strong PL bands at 295, 340, and 395 nm. These bands
blueshift and their intensities decrease after the samples are annealed. When the annealing temperature increases to 1000 °C,
the blueshift becomes specially pronounced and meanwhile the structures of the films develop toward crystalline Al2O3. Based on discussions on the thermal annealing behaviors of the PL and PL excitation spectra, we suggest that optical transitions
in oxygen-related defects, F+ (oxygen vacancy with one electron) centers, are responsible for the observed ultraviolet and violet PL.
Received: 24 July 2000 / Accepted: 24 February 2001 / Published online: 3 May 2001 相似文献
In this paper we consider a random evolution equation with small perturbations, and show how to construct coupled solutions
to the equations. As applications, we prove the Feller continuity of the solutions and the existence and uniqueness of invariant
measures. Furthermore, we establish a large deviations principle for the family of invariant measures as the perturbations
tend to zero.
Received March 20,1998, Accepted June 1, 2000 相似文献
In this paper we present error estimates for the finite element approximation of linear elastic equations in an unbounded domain. The finite element approximation is formulated on a bounded computational domain using a nonlocal approximate artificial boundary condition or a local one. In fact there are a family of nonlocal approximate boundary conditions with increasing accuracy (and computational cost) and a family of local ones for a given artificial boundary. Our error estimates show how the errors of the finite element approximations depend on the mesh size, the terms used in the approximate artificial boundary condition, and the location of the artificial boundary. A numerical example for Navier equations outside a circle in the plane is presented. Numerical results demonstrate the performance of our error estimates.