Avalanche photodiode punch-through gain determination through excess noise analysis

A new approach to determine the multiplication gain at punch-through for an avalanche photodiode with separate absorption and multiplication regions from excess noise measurement is discussed. Correctly determining the gain at punch-through is crucial for characterizing performance parameters of this type of avalanche photodiode. In order to illustrate the viability of this technique, in this work, a Ge on Si avalanche photodiode is analyzed. At a punch-through bias of 15 V, the multiplication gain was determined to be ∼1.54 while a simulation based on the device structure yielded a punch-through gain of 1.65.