Excess Noise Characteristics of Al0:8Ga0:2As Avalanche Photodiodes

The avalanche noise characteristics of Al0 8Ga0 2As have been measured in a range of p-i-n and n-i-p diodes with i-region widths varying from 1.02 to 0.02 m. While thick bulk diodes exhibit low excess noise from electron initiated multiplication, owing to the large ratio (1 ), the excess noise of diodes with 0 31 m were found to be greatly reduced by the effects of dead space. The thinnest diodes exhibit very low excess noise, corresponding to = 0 08, up to a multiplication value of 90. In contrast to most III–V materials, it was found that both thick and thin Al0 8Ga0 2As multiplication layers can give very low excess noise and that electrons must initiate multiplication to minimize excess noise, even in thin structures.