Patent ID: 11923471
Assignee: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 20:
21. A method of making an avalanche diode, comprising:
obtaining or creating a semiconductor structure including:
an n-type (p-type) region;
a p-type (n-type) region; and
a gain region between the n-type region and the p-type region, the gain region buried between the n-type region and the p-type region and the gain region including:
an n+-type region having a higher n-type dopant density than the n-type region;
a p+-type region having a higher p-type dopant density than the p-type region; and
a p-n junction between the n+-type region and the p+-type region;

the surface of the n-type (p-type) region forming a readout structure, comprising:
a plurality of segments in the n-type (p-type) region, each of the segments including an implanted region having a higher dopant density than the n-type (p-type) region;

generating a plurality of first electrodes, wherein at least one of the first electrodes is on each of the segments and the first electrodes on different segments are electrically isolated from one another;
forming a first ohmic contact between each of the implanted regions and the one of the first electrodes on the each of the implanted regions; and
forming a second ohmic contact between the p-type (n-type) region and a second electrode, so that the p-n junction is reverse biased by application of an electric field of appropriate polarity between the first electrodes and the second electrode; and wherein:
a plurality of electrons (holes) is generated in the p-type (n-type) region in response to incident charged particle(s) or photons;
the electrons (holes), accelerated in the reverse bias electric field applied across the gain region, generate additional electrons (holes) in the gain region through impact ionization in the gain region, and
the n-type (p-type) region (including the segments) isolates the first electrodes from electric fields in the gain region so that there is no breakdown between the implanted regions while allowing the additional electrons (holes) to drift from the gain region through the n-type (p-type) region to the first electrodes.