Measurement of Porosity of Porous Silicon Using X-Ray Refraction Effect

A new method for the measurement of porosity in porous silicon , which enables us to determine the porosity of inner layers as well as that of each layer in multilayers using X-ray diffraction, is proposed. This method essentially applies the refraction of X-rays incident on the surface at a very small glancing angle for the separation of diffraction angles. To demonstrate the applicability of this method, the porosities of three samples of monolayers with different porosities and of a sample including multilayers were measured. The obtained values of porosities in monolayers are in good agreement with those obtained by the conventional gravimetric technique, and the value for each layer in the multilayers is consistent with the designed values for the multilayers. Thus, this method yields the porosities of various porous layers nondestructively; this has never been measured by conventional methods.