Wednesday, January 07, 2009

US Patent 7473922 - Stacked quantum dot infrared detector with dark current reducing quantum wells

In photodetectors the dark current is defined as the amount of current flowing when no light is present. For higher sensitivity detectors it is desirable to decrease the dark current and this patent from Fujitsu teaches a quantum dot infrared detector using a quantum well capable of providing reductions in dark current. Claim 1 reads:

1. An infrared detector, comprising:

an infrared detecting section which includes stacked quantum dot layers; and

at least one dark current reducing layer which is provided at an end portion in a stacking direction of said infrared detecting section and has a quantum well structure.

However, one piece of prior art which may have some relevance, but which was not considered during the examination is the article "Low dark current quantum-dot infrared photodetectors with an AlGaAs current blocking layer" published in Applied Physics Letters in 2001.