(WO9517016-A1)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (DE4345378-A1)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (DE4343296-C2)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (JP9506739-W)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (US5702538-A)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (EP734591-B1)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.    (RU2141702-C1)      A novel silicon semiconductor wafer has three abutting single crystal sectors (6,7,8) which has radial boundary faces and lines and which form angles (W6,W7,W8) of less than 180 with one another, two of the boundary faces being prim. twin grain boundaries between two (III) crystal planes.    Also claimed is prodn. of the above wafer.    USE -   For solar cells.    ADVANTAGE -   The wafer permits prodn. of extremely thin solar cells of over 20% efficiency with high yields and without high risk of fracture.