Abstract: A silicon wafer is mirror-polished until obtaining surface roughness Ra of 0.70-1.00 nm, Rq of 0.80-1.10 nm, or Rt of 4.50-7.00 nm. The resulting wafer is heat-treated at a temperature not lower than 1,200.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere. According to another aspect, a silicon wafer is mirror-polished until obtaining surface roughness values Ra' of 0.08-0.70 nm, rms of 0.10-0.90 nm, and P-V of 0.80-5.80 nm in a square area of 90 .mu.m by 90 .mu.m, and surface roughness values Ra' of 0.13-0.40 nm, rms of 0.18-0.50 nm, and P-V of 1.30-2.50 nm in a square area of 500 nm by 500 nm. The resulting wafer is heat-treated at 1,100.degree.-1,300.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere.

Abstract: A deflection device for use in a color television receiver comprises a deflection yoke fitted to a neck portion of the color television receiver having three horizontally arranged electron guns so designed as to emit three electron beams, for deflecting horizontally and vertically said three electron beams emitted onto a fluorescent screen from the electron guns of the color television receiver, and soft magnetic material pieces fitted to an end portion of the deflection yoke nearer to the screen, for locally varying the distribution of a deflection field generated by the yoke so as to correct mis-convergence of said three electron beams occurring at the peripheral portion of the screen.