Reduced photocurrent lag using unipolar solid-state photoconductive detector structures: Application to stabilized n-i-p amorphous selenium

Memory effects in direct detection solid-state photoconductors are attributed to interrupted charge transport by traps in the bulk and result in persistent photocurrent lag and ghosting. The identified sources for image lag following the cessation of x-ray exposure are the inhomogeneous electric field's spatial distribution and the detrapping of the bulk space charge. This work shows that the latter is the dominant mechanism for the persistent photocurrent lag in stabilized n-i-p amorphous selenium photoconductors and proposes unipolar charge-sensing detector design for reducing image lag and improving the temporal performance of direct conversion x-ray imagers.