Graded bandgap photodetector

In a semiconductor avalanche photodetector, a single crystalline semiconductor body comprising:

• a first region of a first conductivity type;
• a second region contiguous with said first region;
• and
• a third region, contiguous with said second region, of a conductivity type opposite to said first conductivity type characterized in that:
• said first region has a wider bandgap than said third region and is capable of absorbing radiation to be detected and generating charge carriers in response thereto;
• and
• said second region comprises a plurality of contiguous zones, one of which is contiguous with said first region and one of which is contiguous with said third region, each of said zones having a bandgap that is graded from a first value in the portion of the zone nearest the first region to a smaller second value in the portion of the zone nearest the third region.

In a semiconductor avalanche photodetector, a semiconductor body comprising:

• a first region of a first conductivity type;
• a second region of a conductivity type opposite to said first conductivity type;
• and
• a graded bandgap region situated between said first and second regions;
• one of said first and second regions being capable of absorbing radiation to be detected and generating charge carriers in response thereto.

In a semiconductor avalanche photodetector, a single crystalline semiconductor body comprising:

• a first region of a first conductivity type;
• a second region contiguous with said first region;
• and
• a third region, contiguous with said second region of a conductivity type opposite to said first conductivity type CHARACTERIZED IN THAT:
• said first region has a greater bandgap energy than said third region and is capable of absorbing radiation to be detected and generating charge carriers in response thereto;
• and
• said second region has a bandgap that is graded from a first bandgap energy near said first region to a second smaller bandgap energy near said third region and is capable of causing the avalanche multiplication of charge carriers therein when said device is under a reverse bias.