Avalanche photodiode for photon counting applications and method thereof

An avalanche photodiode designed for single photon detection applications, comprising:

• an absorption layer defining a tunneling current limit field, ETC;
• at least one intermediate-bandgap transition layer;
• a field control layer having a defined thickness, t, and a defined doping level, ρ;
• a multiplication layer defining a breakdown electric field, Ebd;
• wherein said defined thickness and defined doping of said field control layer are selected so as to generate one of:
• i. an electric field reduction therein of about Ebd±½ LTC;
• and,
• ii. an electric field reduction therein that, together with an electric field reduction in said multiplication layer, provides a total field reduction of about Ebd±½ LTC.

A single photon detection system comprising a collection optics and a photon detector, wherein said photon detector comprises an avalanche photodiode designed for single photon detection applications, said photon detector comprising:

• an absorption layer defining a tunneling onset field;
• at least one intermediate-bandgap transition layer provided over said absorption layer;
• a field control layer provided over said transition layer;
• a multiplication layer provided over said field control layer, said multiplication layer defining a breakdown electric field;
• wherein said field control layer is configured so as to generate one of:
• i. an electric field reduction therein equivalent to said breakdown electric field;
• and,
• ii. an electric field reduction therein that, together with an electric field reduction in said multiplication layer, provides a total field reduction equivalent to said breakdown electric field.