AlGaSb avalanche photodiode exhibiting a very low excess noise factor

An Al0.053Ga0.947Sb avalanche photodiode (APD) has been fabricated and tested. First, measurement of an excess noise factor as well as an ionization rate ratio has been demonstrated. A low excess noise factor of 3.8, which is 1.2 dB lower than the conventional GaInAs APD, has been obtained. From this excess noise factor, the effective value of the hole-to-electron ionization rate ratio (keff) has been determined as high as 5, being in good agreement with the hole-to-electron ionization rate ratio (β/α) given by the multiplication data. This keff value is the highest ever reported for long-wavelength III-V APDs.