Nanowire photo-detector grown on a back-side illuminated image sensor

Abstract

An embodiment relates to a device comprising a substrate having a front side and a back-side, a nanowire disposed on the back-side and an image sensing circuit disposed on the front side, wherein the nanowire is configured to be both a channel to transmit wavelengths up to a selective wavelength and an active element to detect the wavelengths up to the selective wavelength transmitted through the nanowire.

We claim: 
     
         1 . A device comprising a substrate, a waveguide comprising a nanowire disposed on or within the substrate, wherein the nanowire comprises a core; wherein the nanowire is configured to separate at a selective wavelength an electromagnetic radiation incident on the nanowire so that a first portion with wavelengths up to the selective wavelength of the electromagnetic radiation transmits through the core and a second portion with wavelengths beyond the selective wavelength of the electromagnetic radiation transmits outside the core, wherein the devices comprises a back-side illuminated image sensor. 
     
     
         2 . The device of  claim 1 , further comprising a first image sensing circuit configured to detect at least a portion of the first portion of the electromagnetic radiation. 
     
     
         3 . The device of  claim 1 , further comprising a second image sensing circuit configured to detect the second portion of the electromagnetic radiation. 
     
     
         4 . The device of  claim 2 , wherein the first image sensing circuit is in the core. 
     
     
         5 . The device of  claim 3 , wherein the second image sensing circuit surrounds the core. 
     
     
         6 . The device of  claim 1 , further comprising a lens structure or an optical coupler over the nanowire, wherein the lens structure or the optical coupler is operably coupled to the nanowire. 
     
     
         7 . The device of  claim 1 , further comprising an anti-reflective layer disposed on the substrate. 
     
     
         8 . The device of  claim 1 , wherein the first image sensing circuit and the second image sensing circuit are selected from a group consisting of a photodiode, a charge storage capacitor, and combinations thereof. 
     
     
         9 . The device of  claim 1 , further comprising a second image sensing circuit configured to detect at least a portion the second portion of the electromagnetic radiation. 
     
     
         10 . The device of  claim 1 , wherein the selective wavelength is a function of the diameter of the nanowire. 
     
     
         11 . The device of  claim 1 , further comprising a vertical photogate. 
     
     
         12 . The device of  claim 1 , wherein the first imaging circuit comprises a pn or pin junction. 
     
     
         13 . The device of  claim 1 , further comprising a cladding and a metal layer around the core, wherein the core, the cladding and the metal form a capacitor that is configured to collect excitons generated in the nanowire and store charge in the capacitor. 
     
     
         14 . The device of  claim 13 , further comprising metal contacts that connect to the metal layer and nanowire to control and detect the charge stored in the capacitor. 
     
     
         15 . The device of  claim 1 , further comprising a cladding surrounding the core, wherein the cladding comprises a passive waveguide. 
     
     
         16 . The device of  claim 3 , wherein the second image sensing circuit is located on or within the substrate. 
     
     
         17 . A compound light detector comprising at least two different devices, the device comprising a substrate having a front side and a back-side that is exposed to incoming radiation, a waveguide comprising a nanowire disposed on or within the substrate and an image sensing circuit disposed on the front side, wherein the nanowire is configured to be both a channel to transmit wavelengths of the incoming radiation up to a selective wavelength and an active element to detect the wavelengths of the incoming radiation up to the selective wavelength transmitted through the nanowire, and the compound light detector is configured to reconstruct a spectrum of wavelengths of an electromagnetic radiation beam; wherein a region outside the core is configured to be a channel to transmit the wavelengths of the electromagnetic radiation beam that do not transmit through the nanowire. 
     
     
         18 . The compound light detector of  claim 17 , wherein the at least two different devices have nanowires having different diameters. 
     
     
         19 . The compound light detector of  claim 17 , wherein the region comprises cladding comprising more than one layers, wherein the more than one layers have indices of refraction consecutively smaller than an index of refraction the nanowire, wherein the cladding comprises of one or more different materials, wherein the cladding permits electromagnetic radiation of wavelengths beyond the selective wavelength to remains within the cladding and be transmitted to a peripheral photosensitive element. 
     
     
         20 . The compound light detector of  claim 17 , wherein the spectrum of wavelengths comprises wavelengths of visible light, IR or combinations thereof. 
     
     
         21 . The compound light detector of  claim 17 , wherein a first device comprises a core of a different diameter than that of a second device and the spectrum of wavelengths comprises wavelengths of visible light, IR or combinations thereof. 
     
     
         22 . The compound light detector of  claim 17 , wherein the compound light detector is configured to resolve black and white or luminescence information contained in the electromagnetic radiation beam. 
     
     
         23 . The compound light detector of  claim 17 , wherein the compound light detector is configured to detect energies of the electromagnetic radiation of four different ranges of wavelengths. 
     
     
         24 . The compound light detector of  claim 23 , wherein the energies of the electromagnetic radiation of the four different ranges of wavelengths are combined to construct red, green and blue colors. 
     
     
         25 . The compound light detector of  claim 17 , wherein at least some of the at least one of the devices does not include a color or infra-red filter. 
     
     
         26 . The device of  claim 1 , further comprising a color or IR filter. 
     
     
         27 . A device comprising a substrate having a front side, a back-side exposed to incoming radiation comprising infrared light, a waveguide comprising a nanowire disposed on or within the substrate, and an image sensing circuit disposed on the front side, wherein the nanowire is configured to be both a channel to transmit the infrared light and an active element to detect the infrared light. 
     
     
         28 . The device of  claim 27 , further comprising a filter that predominantly cuts off visible light and passes infrared light. 
     
     
         29 . The device of  claim 27 , wherein the nanowire comprises GaAs. 
     
     
         30 . The device of  claim 27 , further comprising a planar photodetector configured to detect infrared light. 
     
     
         31 . The device of  claim 30 , wherein the planar photodetector comprises GaAs. 
     
     
         32 . The device of  claim 27 , wherein the device further comprises a cladding. 
     
     
         33 . The device of  claim 32 , wherein the cladding is configured to be a channel to transmit the wavelengths of the electromagnetic radiation beam that do not transmit through the nanowire. 
     
     
         34 . The device of  claim 32 , and wherein the cladding comprises more than one layers. 
     
     
         35 . The device of  claim 34 , wherein the more than one layers have indices of refraction consecutively smaller than an index of refraction the nanowire. 
     
     
         36 . The device of  claim 27 , wherein the nanowire comprises a semiconductor. 
     
     
         37 . The device of  claim 27 , further comprising a lens structure or an optical coupler over the nanowire, wherein the lens structure or the optical coupler is operably coupled to the nanowire. 
     
     
         38 . The device of  claim 27 , further comprising an anti-reflective layer disposed on the substrate. 
     
     
         39 . The device of  claim 27 , wherein the active element is configured to be a photodiode, a charge storage capacitor, or combinations thereof. 
     
     
         40 . The device of  claim 27 , wherein the device is an image sensor. 
     
     
         41 . The device of  claim 27 , further comprising a vertical photogate. 
     
     
         42 . The device of  claim 27 , wherein the nanowire is configured to convert energy of the electromagnetic radiation transmitted through the nanowire and to generate electron hole-pairs (excitons). 
     
     
         43 . The device of  claim 42 , wherein the nanowire comprises a pn or pin junction that is configured to detect the excitons generated in the nanowire. 
     
     
         44 . The device of  claim 42 , further comprising an insulator layer around the nanowire and a metal layer around the insulator layer to form a capacitor that is configured to collect the excitons generated in the nanowire and store charge in the capacitor. 
     
     
         45 . The device of  claim 44 , further comprising metal contacts that connect to the metal layer and nanowire to control and detect the charge stored in the capacitor. 
     
     
         46 . The device of  claim 32 , wherein the cladding comprises a passive waveguide. 
     
     
         47 . The device of  claim 32 , further comprising a peripheral photosensitive element, wherein the peripheral photosensitive element is operably coupled to the cladding. 
     
     
         48 . The device of  claim 47 , wherein the peripheral photosensitive element is located on or within a substrate.