A compositionally graded sawtooth-bandgap multilayer consisting of In 1 − x − y Ga x Al y As lattice-matched to InP was fabricated by low-pressure metalorganic vapor phase epitaxy for reverse-bias device application. Using this multilayer in a staircase avalanche photodiode with a configuration separating the photo-absorption and multiplication regions resulted in a multiplication factor of over 80 and a multiplied dark current of only 2.2 pA/μm 2. Spectral measurements revealed that the triangular band structure causes the photo-absorption edge red shift due to an electric field to be smaller than that of a rectangular superlattice structure.