EFFECT OF BORON-DIFFUSION DOPING OF SILICON ON THE MICROMECHANICAL AND LUMINESCENT PROPERTIES OF POROUS LAYERS

The effect of boron diffusion on the microhardness and photoluminescen t properties of porous silicon layers obtained conventionally by anode etching is studied. By means of angle lap, it was found that the samp les have a three-layer structure: the upper layer is a transparent fil m, the middle-actually porous silicon, and the lower layer is a single -crystal substrate. It is established that boron diffusion into the ca thode surface increases the luminescence intensity, while diffusion in to the anode surface decreases it, and the thickness of both the porou s and surface silicon compound layers increased in both casts. A concl usion is drawn that the gradient or internal stresses in the substrate produces a positive effect oil the luminescence intensity of the poro us layer grown on it. A luminescence model allowing for both the role of silicon compounds and the quantum-sits hypothesis is proposed. (C) 1998 Published by Elsevier Science S.A.