A numerical model for signal-processing-in-the-element (SPRITE) detect
ors is developed that incorporates both hole and electron motion, the
effects of space charge and varying field, and boundary conditions. Th
e model is used to generate a spatial-frequency response for a rectang
ular SPRITE structure. Further, we use this model to investigate two i
mproved SPRITE structures: the tapered detector and the modulation-dop
ed detector.