Semiconductor substrate and thin-film semiconductive member, and method for making thereof

A semiconductor substrate comprising a porous layer comprising a porous semiconductor containing an impurity with a content of 1×1018 cm−3 or more.

A semiconductor substrate comprising a porous layer provided by pore formation in an epitaxial growth layer.

A thin-film semiconductive member formed on one surface of a supporting substrate with a porous layer provided therebetween, and separated from said supporting substrate by cleavage in said porous layer, said porous layer comprising a porous semiconductor having an impurity concentration varying in the depth direction.

A thin-film semiconductive member formed on one surface of a supporting substrate with a porous layer provided therebetween, and separated from said supporting substrate by cleavage in said porous layer, said porous layer comprising a porous semiconductor having an impurity concentration of 1×1018 cm−3 or more.

A thin-film semiconductive member formed on one surface of a supporting substrate with a porous layer provided therebetween, and separated from said supporting substrate by cleavage in said porous layer, said porous layer being provided by pore formation in an epitaxial growth layer.

A method for making a semiconductor substrate comprising:

• a variant layer forming step for forming a variant impurity layer with an impurity concentration varying in the depth direction on one surface of a supporting substrate;
• and
• a porous layer forming step for forming a porous layer by providing pores in the variant impurity layer by anodic oxidation so that the porosity in the porous layer varies in the depth direction.

A method for making a semiconductor substrate comprising:

• a high-impurity layer forming step for forming a high-impurity layer comprising a semiconductor having an impurity concentration of 1×1018 cm−3 or more on one surface of a supporting substrate;
• and
• a porous layer forming step for forming pores in the high-impurity layer by anodic oxidation to form a porous layer having different porosities in the depth direction.