A semiconductor substrate includes a porous semiconductor having: a porous layer, with an impurity concentration on varying in the depth direction, or having a porous semiconductor containing an impurity with a content of 11018cm3 or more, or provided by pore formation in an epitaxial growth layer. The device includes a tensioning structure for providing adjustable resistance. A method for performing data transactions is presented. The magnetic field component data is transferred through a multiplexer to an analogdigital converter to a processor.