AVALANCHE PHOTODIODES AND METHODS FOR THEIR MANUFACTURE

摘要

AVALANCHE PHOTODIODES AND METHODS FOR THEIR MANUFACTURE An avalanche photodiode has separate absorption and multiplication regions. The photodiode has a first charge sheet located between the absorption region and a central portion of a pn junction of the multiplication region, and a second charge sheet located between the absorption region and edges of the pn junction. The second charge sheet has a lower doping concentration per unit area than the first charge sheet. The first and second charge sheets may be formed by forming a heavily doped semiconductor sublayer, and preferentially removing a portion of the sublayer to leave thicker portion of the sublayer which defines the first charge sheet and a thinner portion of the sublayer which defines the second charge sheet. Another sublayer may then be formed over the charge sheets, and the pn junction may be formed in that sublayer. The photodiode is useful for optical signal detection in optical fiber telecommunications systems.