US 4,198,646 AGranted

Monolithic imager for near-IR

AssigneeHughes Aircraft Company

InventorsDavid H. Alexander, George H. Hershman, Michael D. Jack, N. John Koda, Randahl B. Lloyd

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Abstract

A monolithic imager utilizing a plurality of detector cells is formed on a common intrinsic substrate. Backside illumination in the near-IR region generates hole-electron pairs in the intrinsic material which may be depleted throughout its thickness by CCD-range voltages applied by the imager's readout structure to a over-lying, thinly doped epitaxial layer. Minority carriers migrate toward a collection node which is formed in the epitaxial layer (and protrudes into the substrate), accumulating in an inversion layer at the surface of the epitaxial layer. The accumulated charge is advanced to an output diffusion in the epitaxial layer by means of a readout system which provides semi-random addressing of the transfer gate electrodes of the individual detector cells.

Claims4

Dependent claims

Apparatus for detecting the presence of near-IR radiation and producing a signal responsive thereto comprising:

(a) an intrinsic substrate of a first conductivity type, said substrate having a backside for receiving radiation and an oppositely disposed top surface;
(b) an epitaxial layer of said first conductivity type formed adjacent the top surface of said substrate, said layer containing means for collecting charge carriers and an output diffusion of a second conductivity type;
(c) a readout layer of insulative material formed adjacent said epitaxial layer, said readout layer containing means for transferring the charge carriers collected within said epitaxial layer to said output diffusion;
and
(d) said readout layer additionally having means for imposing a bias so that said intrinsic substrate is depleted of substantially all of the charge carriers generated by near-IR radiation received at the backside thereof, whereby substantially all of said carriers will be collected in said epitaxial layer and transferred to the output diffusion thereof.

2 more elements

Dependencies are inferred from the claim text.