A method for treatment of semiconductor material wherein the material is exposed to electromagnetic radiation having a frequency in the range of the resonance frequency in order to alter the relative positions of interstitial impurity ions and lattice nodes of the interstitial ions. The intensity of the electric field is selected to be proportional to the value of activation barrier potential of the impurity ions. The method is useful in providing accelerated diffusion of a doping impurity, activation of the ions of an implanted impurity, or in creation of metallic ohmic contacts at the surface of the semiconductor material without heating of the semiconductor material.

An efficient method is proposed for the preparation of a silicon single crystal wafer for discrete semiconductor devices, such as transistors, deeply doped with a dopant on one surface, the other surface being mirror-polished. Different from the conventional process in which a single base wafer is subjected to a deposition doping and drive-in doping treatments to form a deeply doped layer on each of the surfaces followed by removal of one of the doped layers and lapping and mirror-polishing the surface, the improvement of the invention can be obtained by subjecting a base wafer having an increased thickness to the deposition and drive-in doping treatments to form deeply doped layers on both surfaces leaving an undoped layer in-between followed by slicing this base wafer by using an annular slicing blade having a thickness specifically correlated to the thickness of the starting wafer along the undoped layer into two separate wafers each having a laminar structure consisting of a doped layer and an undoped layer which are each lapped and mirror polished on the surface of the undoped layer.