A very high charge, high polarization gradient-doped strained GaAs photocathode

A high-gradient-doping technique is applied to strained polarized photocathodes. A 5.0-7.5 nm p-type surface layer doped to 5 x 10(19) cm(-3) is found sufficient to overcome the surface charge limit while maintaining high beam polarization. This technique can be employed to meet the charge requirements of the Next Linear Collider with a polarization approaching 80%. (C) 2002 Elsevier Science B.V. All rights reserved.