AVALANCHE PHOTODIODE

摘要

The purpose of the present invention is to provide an avalanche photodiode (APD) wherein a dark current due to the mesa surface is reduced. An APD (301) is provided with: a semi-insulating substrate (1); a first mesa (101), which is composed of a first laminated configuration wherein a p-type electrode layer (2), a p-type light absorbing layer (3A), a light absorbing layer (3B) having a low impurity concentration, a band gap inclined layer (4), a p-type electric field control layer (5), an avalanche multiplication layer (6), an n-type electric field control layer (7A), and an electron transition layer (7B) having a low impurity concentration are laminated in this order on the surface of the semi-insulating substrate (1); a second mesa (102), which has, when viewed from the lamination direction, the outer circumference inside of the outer circumference of the first mesa (101), and which is composed of a second laminated configuration wherein an n-type electrode buffer layer (8A) and an n-type electrode layer (8B) are laminated in this order on the surface on the electron transition layer (7B) side; and a depletion suppressing region (11), which is formed on a surrounding portion (14) of a layer on the side closer to the second mesa (102) than the p-type electric field control layer (5), said surrounding portion being inside of the outer circumference of the first mesa (101) and surrounding the outer circumference of the second mesa (102), and which prevents the surrounding portion of the p-type electric field control layer (5) from being depleted when a bias is applied.