CMOS sensor with electrodes across photodetectors at approximately equal potential
First Claim
1. A MOS or CMOS based active pixel sensor comprising:
- A) a substrate;
B) an array of pixels fabricated in or on said substrate, each pixel comprising;
1) a pixel electrode and2) integrated pixel circuits,C) a photodiode structure located above said pixel circuits for converting electromagnetic radiation into charges during charge integration cycles, said photodiode structure defining a photodiode region for each of said pixels, said photodiode structure comprising;
1) at least one layer of charge generating material to generate charges upon the absorption of electromagnetic radiation, and2) a surface electrode in the form of a thin transparent layer or grid located above said layers of charge generating material;
wherein each of said integrated pixel circuits;
i) defines;
a) a charge collection node on which charges generated inside the photodiode are collected,b) a charge integration node, at which charges generated in said pixel are integrated to produce pixel signals,c) a charge sensing node from which reset signals or the pixel signals are sensed; and
ii) is adapted to maintain voltage potential drop across said electromagnetic radiation detection structure at less than 1.0 volts and substantially constant during charge integration cycles.
1 Assignment
0 Petitions
Accused Products
Abstract
A MOS or CMOS based active pixel sensor designed for operation with zero or close to zero potential across the pixel photodiodes to minimize or eliminate dark current. In preferred embodiments the pixel photodiodes are produced with a continuous pin or nip photodiode layer laid down over pixel electrodes of the sensor. In this preferred embodiment, the voltage potential across the pixel photodiode structures is maintained constant and close to zero, preferably less than 1.0 volts. This preferred embodiment enables the photodiode to be operated at a constant bias condition during the charge detection cycle. Setting this constant bias condition close to zero (near “short circuit” condition) assures that dark current is substantially zero.
-
Citations
24 Claims
-
1. A MOS or CMOS based active pixel sensor comprising:
-
A) a substrate; B) an array of pixels fabricated in or on said substrate, each pixel comprising; 1) a pixel electrode and 2) integrated pixel circuits, C) a photodiode structure located above said pixel circuits for converting electromagnetic radiation into charges during charge integration cycles, said photodiode structure defining a photodiode region for each of said pixels, said photodiode structure comprising; 1) at least one layer of charge generating material to generate charges upon the absorption of electromagnetic radiation, and 2) a surface electrode in the form of a thin transparent layer or grid located above said layers of charge generating material; wherein each of said integrated pixel circuits; i) defines; a) a charge collection node on which charges generated inside the photodiode are collected, b) a charge integration node, at which charges generated in said pixel are integrated to produce pixel signals, c) a charge sensing node from which reset signals or the pixel signals are sensed; and ii) is adapted to maintain voltage potential drop across said electromagnetic radiation detection structure at less than 1.0 volts and substantially constant during charge integration cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
Specification