US 11,721,780 B2
Avalanche photodetectors with a multiple-thickness charge sheet
Asif Chowdhury, Clifton Park, NY (US); and Yusheng Bian, Ballston Lake, NY (US)
Assigned to GlobalFoundries U.S. Inc., Malta, NY (US)
Filed by GlobalFoundries U.S. Inc., Malta, NY (US)
Filed on Nov. 17, 2021, as Appl. No. 17/528,385.
Prior Publication US 2023/0155050 A1, May 18, 2023
Int. Cl. H01L 31/107 (2006.01); H01L 31/18 (2006.01); H01L 31/0352 (2006.01); H01L 31/028 (2006.01)
CPC H01L 31/1075 (2013.01) [H01L 31/028 (2013.01); H01L 31/035281 (2013.01); H01L 31/1804 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A structure for an avalanche photodetector, the structure comprising:
a first semiconductor layer including a first portion and a second portion, the first portion of the first semiconductor layer defining a multiplication region of the avalanche photodetector;
a second semiconductor layer stacked in a vertical direction with the first semiconductor layer, the second semiconductor layer defining an absorption region of the avalanche photodetector;
a charge sheet in the second portion of the first semiconductor layer, the charge sheet having a thickness that varies with position in a horizontal plane, the charge sheet positioned in the vertical direction between the second semiconductor layer and the first portion of the first semiconductor layer, the charge sheet including a first plurality of doped regions and a doped layer superimposed on the first plurality of doped regions, the first plurality of doped regions and the doped layer each containing a dopant of a first conductivity type, the first plurality of doped regions having a first thickness, and the doped layer having a second thickness that is less than the first thickness; and
a pad comprising a semiconductor material having a second conductivity type different than the first conductivity type,
wherein the first semiconductor layer and the second semiconductor layer are positioned on the pad.