Control of structure and optical anisotropy in porous Si by magnetic-field assisted anodization

Abstract

The effects of an applied magnetic field during anodization on the structural and optical isotropy of luminescent porous silicon (PS) are investigated. The PS layers are prepared by anodizing p-type Si wafers in HF solutions with an external magnetic field of 0–1.7 T applied perpendicular to the Si surface. It is shown that the photoluminescence intensity of PS significantly increases with increasing magnetic field. This effect is accompanied by an increase in both the porosity and the optical isotropy without affecting the surface chemical composition. The structural uniformity in the PS layer and at the PS-substrate interface are also improved. These results suggest that an external magnetic field during anodization regulates the supply of holes from the substrate and produces well-controlled optical and structural properties of PS.