The performance of an optical receiver depends heavily on the excess multiplication noise characteristics of the avalanche photodetector. The excess multiplication noise factor of an avalanche photodiode depends on the ratio of the electron and hole ionization coefficients. The ionization coefficients of 1.06‐&mgr;m photodiodes fabricated from Ga0.72Al0.28Sb have been measured. The results show a hole‐to‐electron ionization‐coefficient ratio of 2, which implies an excess gain noise factorFof 5.9 when the diode is operated at a gain of 10.