Image sensor with phase-sensitive pixels

Imaging apparatus, comprising:

• an illumination source, which is configured to output modulated radiation;
• and
• an image sensor, comprising:
• a photosensitive medium configured to convert incident photons into charge carriers;
• at least one bias electrode, which is at least partially transparent, overlying the photosensitive medium;
• and
• an array of pixel circuits formed on a semiconductor substrate, each pixel circuit defining a respective pixel and comprising a pixel electrode coupled to collect the charge carriers from the photosensitive medium and readout circuitry configured to output a signal responsively to the charge carriers collected by the pixel electrode;
• and
• control circuitry, which is coupled to apply to the at least one bias electrode a potential that is modulated in synchronization with the modulated radiation and causes the voltage between the at least one bias electrode and the at least one pixel electrode to vary periodically between positive and negative values.

A method for imaging, comprising:

• overlaying a bias electrode, which is at least partially transparent, on a photosensitive medium configured to convert incident photons into charge carriers, wherein the photosensitive medium comprises a quantum film, which has a first charge mobility;
• coupling one or more pixel circuits to the photosensitive medium, each pixel circuit defining a respective pixel and comprising first and second pixel electrodes configured to collect the charge carriers from the photosensitive medium at respective first and second locations, which are spaced apart across the pixel, and first and second transfer gates in respective proximity to the first and second pixel electrodes;
• disposing a non-conductive layer, having a second charge mobility, higher than the first charge mobility, between the quantum film and the first and second pixel electrodes;
• and
• applying different, respective first and second potentials to the first and second transfer gates and varying the first and second potentials so as to control relative proportions of the charge carriers that are collected by the first and second electrodes.

A method for imaging, comprising:

• driving an illumination source to output modulated radiation;
• sensing the radiation using an image sensor, which comprises a photosensitive medium configured to convert incident photons into charge carriers, at least one bias electrode, which is at least partially transparent, overlying the photosensitive medium, and an array of pixel circuits, each pixel circuit defining a respective pixel, which are coupled to collect the charge carriers from the photosensitive medium and to output a signal responsively to the collected charge carriers;
• and
• applying to the at least one bias electrode a potential that is modulated in synchronization with the modulated radiation and causes the voltage between the at least one bias electrode and the at least one pixel electrode to vary periodically between positive and negative values.