Abstract: A self-supporting thin film of silicon single crystal is produced essentially by the steps of implanting boron ions in a silicon single crystal substrate from one major surface thereof to form a high impurity concentration layer having a high boron concentration in the substrate; heating the silicon single crystal substrate formed with the high impurity concentration layer in an atmosphere containing oxygen to form an oxide film on the surface of the single crystal substrate and make the high impurity concentration layer resistant to etching; masking all of the oxide film surface other than that at the center region on the surface opposite from that implanted with boron ions and then exposing the high impurity concentration layer by high-speed mask etching followed by selective etching; and removing the oxide film.

Abstract: Radioactive energy is converted to electric energy by irradiating a converter body of semiconductor material etc. with radioactive rays to produce a number of electron-hole pairs in the converter, applying a magnetic field to the converter in a direction perpendicular to the direction of diffusion of the electron-hole pairs to separate the electrons and the holes in a direction perpendicular to the direction of diffusion of the electron-hole pairs and to the direction of application of the magnetic field and deriving the electrons and the holes from electrodes provided on the respective end faces of the converter body as electric energy.