Digital Alloy InAlAs Avalanche Photodiodes

InAlAs digital alloy avalanche photodiodes exhibit lower excess noise than those fabricated from conventional random alloy material. Experiment and Monte Carlo simulation both show that relative to the random alloy the ionization probability for electrons is slightly lower while that of holes is greatly suppressed. We propose that the suppression of carrier ionization probability in digital alloys happens because of the creation of minibands that localize carriers. The difference of suppression between conduction hands and valence hands comes from the difference of scattering path.