Avalanche photodiode with mesa structure - including guard ring preventing edge breakdown

摘要

An avalanche photodiode has, on a III-V semiconductor substrate (17), weakly doped first conductivity type absorption (27) and intermediate (47) layers, a highly doped opposite second conductivity type cover layer (67) as the uppermost grown semiconductor layer, a multiplication layer (57) which has higher first conductivity type doping than the intermediate layer (47) and which is located between the intermediate (47) and cover (67) layers, a second conductivity type doped guard ring (1), a first contact (37) having a light inlet opening and formed on the cover layer (67), and a second contact (97) applied onto part of the first conductivity type doped semiconductor material. The novelty is that (i) at least the multiplication (57) and cover (67) layers are grown on top of one another and are formed as a mesa; (ii) the guard ring (1) has a low second conductivity type doping level and is formed as an annulus in the mesa; (iii) the guard ring (i) extends from the cover layer surface, opposite the multiplciaton layer, at least to the intermediate layer (47); and (iv) the portion of the cover layer (67) within the guard ring (i) is provided for light entry. Prodn. of the avalanche photodiode is also claimed. ADVANTAGE - Edge breakdown is effectively prevented and the photodiode is simple to produce.