Christopher Thomas Lang

US Patent:

8618625, Dec 31, 2013

Filed:

Mar 2, 2011

Appl. No.:

13/038470

Inventors:

Vipulkumar Patel - Breinigsville PA, US
Prakash Gothoskar - Allentown PA, US
Mark Webster - Bethlehem PA, US
Christopher J. Lang - New Tripoli PA, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H01L 31/0224

US Classification:

257454

Abstract:

A planar, waveguide-based silicon Schottky barrier photodetector includes a third terminal in the form of a field plate to improve the responsivity of the detector. Preferably, a silicide used for the detection region is formed during a processing step where other silicide contact regions are being formed. The field plate is preferably formed as part of the first or second layer of CMOS metallization and is controlled by an applied voltage to modify the electric field in the vicinity of the detector's silicide layer. By modifying the electric field, the responsivity of the device is “tuned” so as to adjust the momentum of “hot” carriers (electrons or holes, depending on the conductivity of the silicon) with respect to the Schottky barrier of the device. The applied potential functions to align with the direction of momentum of the “hot” carriers in the preferred direction “normal” to the silicon-silicide interface, allowing for an increased number to move over the Schottky barrier and add to the generated photocurrent.