  The spin lifetime and Hanle signal amplitude dependence on bias current has
been investigated in insulating Al$_{0.3}$Ga$_{0.7}$As:Si using a
three-terminal Hanle effect geometry. The amplitudes of the Hanle signals are
much larger for forward bias than for reverse bias, although the spin lifetimes
found are statistically equivalent. The spin resistance-area product shows a
strong increase with bias current for reverse bias and small forward bias until
150 $\mu$A, beyond which a weak dependence is observed. The spin lifetimes
diminish substantially with increasing bias current. The dependence of the spin
accumulation and lifetime diminish only moderately with temperature from 5 K to
30 K.
