Hetero-interface avalance photodetector

A photodetector comprising:

• an absorption region made from a first semiconductor material, said absorption region configured to photogenerate charge carriers in response to incident light;
• a multiplication region made from a second semiconductor material configured to receive at least a fraction of said photogenerated charge carriers, and comprising a p-n junction to substantially multiply the number of charge carriers by avalanche multiplication, said p-n junction having an unbiased depletion width;
• and
• contacts for applying a reverse bias voltage across said photodetector,
• wherein said regions are in physical proximity, said semiconductor materials have lattice constants which differ from each other by more than 1%, and wherein said p-n junction is at a distance greater than said unbiased depletion width away from said absorption region.

A photodetector comprising:

• an absorption region made from a first semiconductor material, said absorption region configured to photogenerate charge carriers in response to incident light;
• a multiplication region made from a second semiconductor material configured to receive at least a fraction of said photogenerated charge carriers, said multiplication region comprising a p-n junction to substantially multiply the number of charge carriers by avalanche multiplication, and
• contacts for applying a reverse bias voltage across said photodetector,
• wherein said semiconductor materials have lattice constants which differ from each other by more than 1% and the region of lowest doping of the p-n junction is adjacent to the absorption region, such that an electric field maximum for said applied reverse bias voltage is located in said multiplication region a substantial distance away from said absorption region, and as said reverse bias voltage increases electric fields in said photodetector increase and move toward said absorption region.

A photodetector comprising:

• an n+ type silicon substrate;
• a p− type epitaxial silicon layer grown on said n+ type silicon substrate;
• a n-type InGaAs absorption layer bonded to said p− type epitaxial silicon layer;
• a first contact formed on said n+ type silicon substrate;
• and
• a second contact formed on said n-type InGaAs absorption layer,
• wherein in operation of said photodetector a reverse bias voltage is applied across said contacts causing an electric field maximum at about the interface between said n+ type silicon substrate and said p− type epitaxial silicon layer.