  Model calculation and experimental data of
circularly-polarized-light-dependent photocurrent in a n-AlGaAs/p-InGaAs/p-GaAs
heterostructure are reported. It is found that, under the appropriate forward
bias condition, spin voltaic effect (SVE) can survive across the heterojunction
and give rise to detectable polarization-dependent photocurrent signals which
are greater than the signals due to the magnetic circular dichroism. Our
analysis suggests that SVE can be enhanced by optimization of layer thickness,
doping profile, and applied bias, making SVE favorable for the realization of a
semiconductor-based polarization detector, a spin-photodiode (spin-PD).
