Photodevice detects color with metal grating

September 03, 2014 // By Peter Clarke
Researchers at Rice University (Houston, Texas) have created a CMOS-compatible, a color photodetector that uses aluminium grating technology rather than color filters to make the sensor respond to red, green and blue light.

The researchers make the point that the approach is closer to that used by human eye and allows color selectivity to be integrated into the photodetector.

The device uses two Schottky junctions to accumulate charge in an energy well which results in photocurrent gain and a plasmonic aluminum grating for photocurrent enhancement and red–green–blue color selectivity. The device is described online in a new study in the journal Advanced Materials.

Conventional CMOS image sensors are turned into color image detectors by adding dielectric or dye color filters, which have the disadvantage of requiring multipass processing, tend to degrade under exposure to sunlight and can be difficult to align with the sensor pixels.

Following research at Rice University Image sensors could amplification and filtering integrated directly into pixels. Source: Bob Zheng/Rice University.

Researcher Bob Zheng was looking into camouflage systems and came up with a color photodetector that uses a combination of band engineering and plasmonic gratings, comb-like aluminum structures with rows of parallel slits. The aluuminum is deposited on top of a thin oxide coating on top of the sensor pixel array.