(DE4019219-C)      A process for producing a substrate for selective crystal growth, includes subjecting a substrate with a number of layers, to an electric field. The first substrate layer consists of a material with a high seeding density. A second material is located on top and has a lower seeding density. The electric field is concentrated over a region of the second layer, and the region is removed leaving an area of the primary layer exposed.    ADVANTAGE -   The process can be carried out continuously and is suitable for mass prodn.    (US5098850-A)      Process comprises applying an electric field to a substrate having a 1st layer having a higher nucleation density and an insulating layer having a lower nucleation density, the field being concentrated at a desired region of the 21nd layer to remove it and expose the 1st material. The 1st material is electroconductive. The voltage is above 50 to below 100% of the dielectric breakdown strength of the 2nd material and is applied using a columnar shape contact point.    USE/ADVANTAGE -   Used for producing a substrate for selective crystal growth for a solar battery having good characteristics with sufficient bulk productivity. Photolithography is not required.    (JP2746312-B2)      (A) A substrate for selective crystal growth is produced from a substrate having a layer of high nucleation density material and an overlying layer of low nucleation density material by generating an electric fluid which is concentrated in a desired region of the low nucleation density layer so that this region is removed to expose the high nucleation density layer. (B) A selective crystal growth process comprises carrying out process (A) to expose a small area of the high nucleation density layer, thus forming only a single seed from which a single crystal is grown, the seed being formed by a gas phase crystal growth method and a crystal being allowed to grow outwards from the seed. (C) A solar battery prodn. process comprises carrying out process (B) to form a semiconductor layer region.    (D) Also claimed is prodn. of a solar battery by (a) continuously moving an electrically conductive substrate within a reduced pressure chamber and forming a layer with a non-nucleating surface on the substrate surface; (b) generating a concentrated or punctiform electric field to remove a desired region of the layer and expose a substrate region sufficiently small to form only a single seed from which a single crystal is grown; (c) carrying out a crystal growth process to grow a crystal outwards from the seed; (d) growing, on the crystal, a further-crystal of different conductivity type; and (e) forming electrodes by forming an electrically conductive layer on this different conductivity type crystal.    ADVANTAGE -   Non-nucleating and nucleating surfaces are produced continuously on substrates without direct use of photolithography. Solar batteries, with good properties can be mass produced with satisfactory productivity.