A method (I) of manufacturing a solar cell comprises: (a) forming a first alloy of a first metal and a first dopant capable of doping a semiconductor to be of a first type; (b) applying said alloy to a semiconductor surface which has been doped to be of a second type opposite to said first type; (c) heating the alloy and semiconductor so that at least a portion of each form a molten second alloy; (d) cooling the second alloy so that at least a portion of the first dopant is incorporated in an epitaxial regrowth region of the first semiconductor such that at least a portion of said region forms a rectifying junction with said first semiconductor and at least a portion of said junction is exposed to solar radiation that has not passed through said region; (e) cooling the second alloy to form a solid first contact with ohmic contact to at least a portion of said region; and (f) applying an ohmic contact to the first semiconductor to form a second electrical contact of the cell    Also claimed is a method (II) of manufacturing a solar cell comprising: (a) forming a rectifying junction comprising first and second halves in a semiconductor which generates electrical current upon exposure to solar radiation; (b) forming a first ohmic contact to said first half; (c) proceeding as steps (a)-(d) of (I) such that the regrowth region has greater dopant concentration than the first region; (d) cooling the second alloy to form a second ohmic contact to at least a portion of the regrowth region where said second contact has ohmic contact to said second half.    Also claimed is a method (III) of manufacturing a contact comprising: (a) forming a first paste, comprising first granules, each comprising an alloy of a first metal and a first dopant; (b) applying the paste to a semiconductor surface; (c) heating the paste and semiconductor so that at least a portion of them form a molten second alloy; (d) cooling the second alloy so at least a portion of dopant is incorporated into an epitaxial regrowth region of the semiconductor; (e) cooling the first alloy to form a solid ohmic contact to at least a portion of the regrowth region.    Also claimed is a method of manufacturing a contact comprising: (a) applying a metal to a first region semiconductor surface; (b) heating the metal and semiconductor, in an ambient gas atmosphere so at least a portion of them form a molten second alloy; (c) introducing vaporised dopant into said gas; (d) maintaining the temperature to allow sufficient dopant to be absorbed into the second alloy; (e) cooling the alloy as in (III) (d); (f) further cooling the alloy to form a contact as in (III) (e).    Also claimed are two solar cells made by methods similar to (II).    USE -   Used for silicon solar cells and other silicon devices.    ADVANTAGE -   The invention provides a self-doping negative or positive electrode which may be formed simultaneously in a single high temperature step.