Optoelectronic detector with multiple readout nodes and its use thereof

• US 7,521,663 B2
• Filed: 09/18/2003
• Issued: 04/21/2009
• Est. Priority Date: 09/18/2003
• Status: Active Grant

• Current Assignee: Ams Sensors Singapore Pte. Ltd. (Ams-Osram AG)
• Original Assignee: MESA IMAGING AG (Ams-Osram AG)
• Inventors: Wäny, Martin
• Primary Examiner(s): Pyo; Kevin
• Application Number:
  US10/572,108
• Publication Number:
  US 20070176079A1
• Time in Patent Office: 2,042 Days
• Field of Search: 250/214.1, 250/208.1, 250/214.R, 257229-230, 257/448, 327/514
• US Class Current: 250/214.1
• CPC Class Codes: H01L 27/14601 Structural or functional details thereof
• CPC Class Codes: H04N 25/71 Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 3/1525 with charge transfer within the image-sensor, e.g. time delay and integration H04N3/1575 takes precedence

Abstract

The present invention discloses an optoelectronic detector for light sensing. The optoelectronic detector has a photosensitive element that converts light into electrons. Efficient collection of these electrons at readout nodes, embedded in the photosensitive element, is required to make correct measurements of light characteristics such as, phase shift and intensity. This collection of electrons is achieved by applying a voltage gradient across an electrode within the optoelectronic detector. The optoelectronic detector can have multiple readout nodes. Further, the present invention discloses methods for detecting intensity and phase shift of impinging light and for suppression of background illumination while detecting the characteristics of light.

Claims

1. A method for suppression of background illumination in modulated light using an optoelectronic detector, the detector having a photosensitive substrate, a plurality of readout nodes and a plurality of means for steering free electrons to one of the readout nodes, the method comprising the steps of:

a. determining a switching sequence, the switching sequence being synchronized with the modulation frequency of the light, the switching sequence comprising periods in which light is present along with background illumination and a period in which only background illumination is present;

b. identifying a readout node corresponding to the period in which only background illumination is present;

c. activating a light source, the activation leading to impingement of modulated light on the photosensitive substrate, the impingement resulting in generation of free electron-hole pairs in the photosensitive substrate;

d. steering free electrons to one of the readout nodes according to the switching sequence, the free electrons being steered to the identified readout node during the period in which only background illumination is present; and

e. draining free electrons collected at the identified readout node.

2. The method according to claim 1 wherein the step of determining a switching sequence comprises the steps of:

a. determining modulation frequency of the modulated light; and

b. determining a time period using the determined modulation frequency.

3. The method according to claim 1 wherein the step of identifying the readout node corresponding to the period in which only background illumination is present comprises the steps of:

a. determining the time period during which light is absent; and

b. determining the readout node to which electrons are steered during the determined time period.

4. The method according to claim 1 wherein the step of steering free electrons to a readout node comprises generating potential gradient across a pair of readout nodes.

5. The method according to claim 4 wherein the step of generating potential gradient comprises the step of applying voltage gradient across the corresponding means for steering free electrons.

6. The method according to claim 1 wherein the step of draining free electrons at a readout node comprises the step of connecting the readout node to a source of reset potential.