We report use of InAs/AlSb superlattice as the n-type layer in an all molecular beam epitaxially grown, antimonide avalanche photodetector. N-type doping of the superlattice was achieved by selectively incorporating Si in the InAs layer. The superlattice was grown lattice matched to the GaSb substrate and exhibited sharp X-ray diffraction satellite peaks. By using the superlattice as part of the one-sided abrupt junction, p(-)n(+) avalanche photodiodes with Al,.,,Ga,,,Sb multiplication regions were fabricated. The device dark current was found to be highly dependent on the superlattice period and the resulting band offset at the superlattice/multiplication layer interface. Near infrared photo gains of up to 30 and a dark current density of 6 A/cm(2) at a gain factor of 10 were observed for structures with an optimized, there stage InAs/AlSb superlattice.