Molecular shift register based on electron transfer
AssigneeCalifornia Institute of Technology
InventorJohn J. Hopfield
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Abstract
An electronic shift register memory (20) at the molecular level is described. The memory elements are based on a chain of electron transfer molecules (22) and the information is shifted by photoinduced (26) electron transfer reactions. The device of the invention integrates designed electronic molecules onto a VLSI substrate (36), providing an example of a "molecular electronic device" which may be fabricated.
Claims20
An electronic shift register comprising (a) a plurality of molecular devices formed on a semiconductor substrate which also supports a VLSI circuit, to which said molecular devices are electrically and logically connected, said molecular devices comprising a polymer made up of a plurality of monomeric repeat units, each monomeric repeat unit comprising at least three different monomers, with at least one monomer characterized by an electron energy level having a ground state and an upper state to which electrons may be excited and at least one of the remaining monomers characterized by an electron energy level having a ground state only to permit movement of an electron in a predetermined direction, and (b) pulsed light means for exciting an electron to said upper state when light is one and for permitting said electron to decay to a ground state of an adjacent monomer when light is off.
An electronic shift register comprising (a) a plurality of molecular devices formed on a semiconductor substrate which also supports a VLSI circuit, to which said molecular devices are electrically and logically connected, said molecular devices comprising a polymer made up of a plurality of monomeric repeat units, each monomeric repeat unit comprising at least three different monomers, with one monomer characterized by an electron energy level having a ground state and an upper state to which electrons may be excited and the remaining monomers characterized by an electron energy level having a ground state only to permit movement of an electron in a predetermined direction, and (b) pulsed light means for exciting an electron to said upper state when light is on and for permitting said electron to decay to a ground state of an adjacent monomer when light is off.
A molecular circuit for a shift register comprising a plurality of substantially parallel polymer chains, each polymer chain of the same length as the other polymer chains and comprising a plurality of repeat monomeric units, each monomeric repeat unit comprising at least three different monomers, with at least one monomer characterized by an electron energy level having a ground state and an upper state to which electrons may be excited and the remaining monomers characterized by an electron energy level having a ground state, said molecular circuit adapted to be responsive to pulsed light for exciting an electron to said upper state when light is on and for permitting said electron to decay to a ground state of an adjacent monomer when light is off.
A method of storing and transferring information in a shift register comprising a plurality of molecular devices on a semiconductor substrate which also supports a VLSI circuit, to which said molecular devices are electrically and logically connected, said molecular devices each comprising a plurality of polymeric strands, each polymeric strand made up of a plurality of monomeric repeat units, each monomeric repeat unit comprising at least three different monomers, with one monomer characterized by an electron energy level having a ground state and an upper state to which electrons may be excited and the remaining monomers characterized by an electron energy level having a ground state, one end of each polymeric strand attached to a conductive source electrode, and the opposite end of each polymeric strand attached to a conductive receiving electrode, said method comprising:
- (a) immersing said substrate in an electrolyte;
- and
- (b) exciting the molecular devices with intense short pulses of light to cause an electron to be excited to an upper state on one monomer and to decay through successive monomers to the next monomer repeat unit, such that one pulse of light moves an electron from one repeat unit to the next.
A method of storing and transferring information in a shift register comprising a plurality of molecular devices on a semiconductor substrate which also supports a VLSI circuit, to which said molecular devices are electrically and logically connected, said molecular devices each comprising a plurality of polymeric strands, each polymeric strand made up of a plurality of monomeric repeat units, each monomeric repeat unit comprising at least three different monomers, with two monomers characterized by an electron energy level having a ground state and an upper state to which electrons may be excited, the difference between said ground state and said upper state being different for said two monomers, and the remaining monomers characterized by an electron energy level having a ground state, one end of each polymeric strand attached to a conductive source electrode, and the opposite end of each polymeric strand attached to a conductive receiving electrode, said method comprising:
- (a) immersing said substrate in an electrolyte;
- and
- (b) exciting the molecular devices with intense pulses of light of alternating wavelengths to cause an electron to be excited to an upper state in a first monomer, then to cause an electron to be excited to an upper state in a second monomer and to decay through successive monomers to the next monomer repeat unit, such that two alternating pulses of light of different wavelengths move an electron from one repeat unit to the next.
Dependencies are inferred from the claim text.