Solid-state image pickup device
The present invention provides a solid state image pickup device, including a silicon substrate and a photoelectric conversion unit which receives external incident light and generates signals in accordance therewith, and which is formed on or above the surface of the silicon substrate, wherein a signal transmission circuit for reading out the signals generated in the photoelectric conversion unit is formed on the silicon substrate; the photoelectric conversion unit includes a photoelectric conversion layer which has a laminated structure of plural compound semiconductor layers, which are different from each other in light wavelength to absorb and are provided with the laminated structure so that the shorter a light absorption wavelength of a compound semiconductor layer is, the closer to a light incident side the compound semiconductor layer resides; and the plural compound semiconductor layers are respectively connected to pixel electrodes formed on the signal transmission circuit.
1 . A solid state image pickup device, comprising a silicon substrate and a photoelectric conversion unit which receives external incident light and generates signals in accordance therewith, and which is formed on or above the surface of the silicon substrate, wherein
a signal transmission circuit for reading out the signals generated in the photoelectric conversion unit is formed on the silicon substrate;
the photoelectric conversion unit comprises a photoelectric conversion layer which comprises a laminated structure of plural compound semiconductor layers, which are different from each other in light wavelength to absorb and are provided within the laminated structure so that the shorter a light absorption wavelength of a compound semiconductor layer is, the closer to a light incident side the compound semiconductor layer resides; and
the plural compound semiconductor layers are respectively connected to pixel electrodes formed on the signal transmission circuit.
2 . The solid state image pickup device according to claim 1 , wherein
the photoelectric conversion layer comprises a laminated structure of first to third compound semiconductor layers arranged in this order along a light-incident direction;
the first compound semiconductor layer comprises an InAlP layer;
the second compound semiconductor layer comprises an InGaAlP layer; and
the third compound semiconductor layer comprises a layer selected from the group consisting of an InGaP layer, a GaAs layer and an InGaAsP layer.
3 . The solid state image pickup device according to claim 2 , wherein the first compound semiconductor layer has a band gap within a range of 440 to 480 nm;
the second compound semiconductor layer has a bang gap at 520 to 580 nm; and
the third compound semiconductor layer has a band gap within a range of 600 nm or greater wavelength region.
4 . The solid state image pickup device according to claim 2 , wherein the third compound semiconductor layer contains an InGaP layer.
5 . The solid state image pickup device according to claim 1 , wherein a light-shielding film is formed on or above the photoelectric conversion unit except for a light-receiving surface of the photoelectric conversion unit.
6 . The solid state image pickup device according to claim 1 , wherein a microlens is formed on or above a light-receiving surface of the photoelectric conversion unit.
7 . A process for producing the solid state image pickup device according to claim 1 , wherein the compound semiconductor layers are formed by organic metal gas-phase growth or molecular beam epitaxial growth.