Ferroelektrische Halbleiter

1167235 Ferro-electric semi-conductors ATOMIC ENERGY OF CANADA Ltd 23 Aug 1967 [14 Sept 1966] 38874/67 Headings H3U UN U22 U30 U28 and U34 A ferro-electric semi-conductor is composed of a compound of elements from Groups IV B and VI B of the Periodic Table, having atomic weights greater than 16, the material being doped to provide regions of differing carrier type. The preferred materials are germanium telluride or a solid solution of germanium telluride and tin telluride in a 30:70 molecular percentage ratio. Lead telluride is also referred to. Pressure sensitive devices may be made from such materials. The example shown comprises an NPN (or PNP) device formed by suitably doping an intrinsic ferro-electric semiconductor, pressure being applied to an emitter junction 42. In a second embodiment an acoustic wave is amplified within such a material by the interaction of this wave with carriers drifting in a steady electric field at a velocity slightly greater than that of the acoustic wave. The ferro-electric semi-conductor may be used in single crystal form, or as polycrystalline material dispersed in a glass or ceramic matrix. The material is prepared by purification and diffusion, and is then heated above its Curie temperature and cooled in the presence of an electric field, thereby inducing a remanent polarization which enhances the pressure-sensitivity of the material.