NOISE CHARACTERISTICS OF THIN MULTIPLICATION REGION GAAS AVALANCHE PHOTODIODES

It is well known that the gain-bandwidth product of an avalanche photo diode can be increased by utilizing a thin multiplication region. Prev iously, measurements of the excess noise factor of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption and multiplication regi ons indicated that this approach could also be employed to reduce the multiplication noise. This letter presents a systematic study of the n oise characteristics of GaAs homojunction avalanche photodiodes with d ifferent multiplication layer thicknesses. It is demonstrated that the re is a definite ''size effect'' for multiplication regions less than approximately 0.5 mu m. A good fit to the experimental data has been a chieved using a discrete, nonlocalized model for the impact ionization process. (C) 1996 American Institute of Physics.