Friday, November 13, 2015

Vertical Silicon Nanowires in Color Filters

Harvard University publishes a PhD Thesis "Vertical Silicon Nanowires for Image Sensor Applications" by Hyunsung Park, dated by Sept. 2014. The nanowire filters have demonstrated quite small pixel size and good selectivity:

8 comments:

  1. Very nice work, and nice dissertation write up. Thanks Vlad for finding this.

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  2. He also did works using those SiNW(this might be more important!) as photo detector in thesis. it looks he did not normalized the response to unit area, if so the A/W can be larger.

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  3. what's the benefit for this compare to RGB/CMY color filter? the SNR from this should be very bad due to high cross talk.

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    1. One example is given in the thesis: one wavelenth is absorbed in the little pins (sensor 1) and the other in the base. This means all light on the area could be used. How to integrate it into readout? I have no idea, but hey, it is fundamental research.

      Or it could be that it is all-silicon. In the end easier to make.

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  4. Does this method use the wave nature of light to separate colours, or the particle nature?

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    1. In think it like Pachinko, and depending on the wire size, big photons go one way, and smaller photons go the other way.

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  5. Interesting Image on Page 11, tells the tail.

    It's great that one can do this, great discovery, enjoy innovation, good to know; but what is it 'better' than (apples to apples, a very similar technology).

    Vertical NWs present a manufacturing challenge (see Image referred to above) over horizontal NWs and don't offer near the capability; this was missing from the Citations: http://www.nature.com/articles/srep12450 where dynamic subtractive color filters are implemented using aluminum nanowires, placed horizontally.

    I think manipulating the vertically placed wires (by some means not covered in the 'Tuition Funding Request') to dynamically influence their effect will, by definition, by more difficult with vertically placed wires.

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    1. Maybe that Nature article was not cited because it came 7 months AFTER the thesis work.

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