Electron paramagnetic resonance in heat-treated porous silicon

Abstract
Electron paramagnetic resonance(EPR) of centers produced in porous silicon(PS) by heat treatment in air is investigated. The properties of these centers are compared with the defects present in as‐prepared PS or activated by treatment of the specimens with ethanol. The native defects of PS and those produced by thermal annealing show different saturation behavior of the EPRspectra when the microwave power is increased. Also, their spin‐dependent recombination processes are different. The dependence of the EPR line intensity on the thermal annealing time at temperatures of 150–500 °C obeys a law characteristic to a diffusion process with an activation energy of 0.9 eV. This value is close to the activation energy of oxidation of crystalline siliconsurfaces with atomic oxygen.