Imaging systems with improved near-infrared detection pixels

An array of image sensor pixels that are configured to generate charge in response to incident light, the array of image sensor pixels comprising:

• first image sensor pixels that are configured to generate charge in response to light of a first color;
• second image sensor pixels that are configured to generate charge in response to light of a second color;
• infrared image sensor pixels that are configured to generate charge in response to infrared light, wherein each of the infrared image sensor pixels comprises:
• a semiconductor layer having opposing first and second surfaces, wherein the incident light passes through the first surface,
• a frontside reflector and a backside reflector, wherein the semiconductor layer is interposed between the frontside reflector and the backside reflector, and
• a microlens that overlaps the semiconductor layer, the frontside reflector, and the backside reflector and that is configured to direct light into the semiconductor layer;
• and
• third image sensor pixels that are configured to generate charge in response to light of a third color, wherein the first, second, third, and infrared image sensor pixels are arranged in a two-by-two unit cell that repeats across the array of image sensor pixels.

An image sensor pixel that is configured to generate charge in response to infrared light, the image sensor pixel comprising:

• a photosensitive region having opposing first and second surfaces, wherein a portion of the first surface of the photosensitive region forms a recess;
• a toroidal microlens overlapping the photosensitive region;
• a first reflector interposed between the toroidal microlens and the first surface of the photosensitive region, wherein at least a portion of the first reflector extends into the recess;
• and
• a second reflector adjacent to the second surface of the photosensitive region.