  The spin Hall effect is investigated in a high mobility two dimensional
electron system with the spin-orbital coupling of both the Rashba and the
Dresselhaus types. A spin current perpendicular to the electric field is
generated by either the Rashba or the Dresselhaus coupling. The spin Hall
conductance is independent of the stength of the coupling, but its sign is
determined by the relative ratio of the two couplings. The direction of spin
current is controllable by tuning the magnitude of the surface electric field
perpendicular to the two dimensional plane via adjusting the Rashba coupling.
It is observed that the spin Hall conductance has a close relation to the Berry
phase of conduction electrons.
