Materials, Fabrication Equipment, and Methods for Stable, Sensitive Photodetectors and Image Sensors Made Therefrom

• US 20100019334A1
• Filed: 07/20/2009
• Published: 01/28/2010
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: InVisage Technologies, Inc. (Apple Inc.)
• Original Assignee: InVisage Technologies, Inc. (Apple Inc.)
• Inventors: Ivanov, Igor Constantin, Sargent, Edward Hartley, Tian, Hui
• Granted Patent: US 8,203,195 B2
• Time in Patent Office: Days
• US Class Current: 257/432
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 31/0224 Electrodes
• CPC Class Codes: H01L 31/032 including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
• CPC Class Codes: H01L 31/0324 comprising only AIVBVI or AIIBIVCVI chalcogenide compounds, e.g. Pb Sn Te
• CPC Class Codes: H01L 31/0336 in different semiconductor regions, e.g. Cu2X/CdX hetero- junctions, X being an element of Group VI of the Periodic Table
• CPC Class Codes: H01L 31/035218 the quantum structure being quantum dots
• CPC Class Codes: H01L 31/03845 comprising semiconductor nanoparticles embedded in a semiconductor matrix in insulating matrix H01L31/0384
• CPC Class Codes: H01L 31/09 Devices sensitive to infrared, visible or ultraviolet radiation H01L31/101 takes precedence
• CPC Class Codes: H01L 31/101 Devices sensitive to infrared, visible or ultraviolet radiation
• CPC Class Codes: H01L 31/109 the potential barrier being of the PN heterojunction type
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

Optically sensitive devices include a device comprising a first contact and a second contact, each having a work function, and an optically sensitive material between the first contact and the second contact. The optically sensitive material comprises a p-type semiconductor, and the optically sensitive material has a work function. Circuitry applies a bias voltage between the first contact and the second contact. The optically sensitive material has an electron lifetime that is greater than the electron transit time from the first contact to the second contact when the bias is applied between the first contact and the second contact. The first contact provides injection of electrons and blocking the extraction of holes. The interface between the first contact and the optically sensitive material provides a surface recombination velocity less than 1 cm/s.

Claims

1. An optically sensitive device comprising:

a first contact and a second contact, each having a work function;

an optically sensitive material between the first contact and the second contact, the optically sensitive material comprising a p-type semiconductor, and the optically sensitive material having a work function;

circuitry configured to apply a bias voltage between the first contact and the second contact;

the magnitude of the work function of the optically sensitive material being at least 0.4 eV greater than the magnitude of the work function of the first contact, and also at least 0.4 eV greater than the magnitude of the work function of the second contact;

the optically sensitive material having an electron lifetime that is greater than the electron transit time from the first contact to the second contact when the bias is applied between the first contact and the second contact;

the first contact providing injection of electrons and blocking the extraction of holes; and

the interface between the first contact and the optically sensitive material providing a surface recombination velocity less than 1 cm/s.

2. The device of claim 1, wherein the work function of the first contact and the second contact are each shallower than 4.5 ev.

3. The device of claim 1, wherein the bias is in the range of about −

0.1 Volts to −

2.8 Volts.

4. The device of claim 1, wherein the optically sensitive material comprises a plurality of nanoparticles, wherein each of the nanoparticles has an oxide on a surface of the respective nanoparticle.

5. The device of claim 1, wherein the optically sensitive material comprises nanoparticles selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, Si, Ge, or C.

6. The device of claim 5, wherein the optically sensitive layer further comprises a material selected from the group consisting of PbSO4, PbO, PbSeO4, PbTeO4, SiOxNy, In2O3, sulfur, sulfates, sulfoxides, carbon and carbonates.

7. The device of claim 1, wherein the optically sensitive material comprises a plurality of interconnected nanoparticles.

8. The device of claim 1, wherein the first contact and the second contact each comprise a material selected from the group consisting of Al, Ag, In, Mg, Ca, Li, Cu, Ni, NiS, TiN, TaN, TiO2, TixNy, ITO, Ru, TiSi, WSi2, TiOx doped with B, TiOx doped with C, TiOx doped with Co, TiOx doped with Fe, TiOx doped with Nd, TiOx doped with N.

9. The device of claim 1, wherein the first contact and the second contact are separated by a distance in the range of 200 nm to 2 um and the electron mobility in the optically sensitive material is at least 1 E-5 cm2/Vs.

10. The device of claim 1, wherein the optically sensitive material is configured to provide a responsivity of at least 0.8 A/W when the bias is applied between the first contact and the second contact.

11. An optically sensitive device comprising:

a first contact;

an n-type semiconductor;

an optically sensitive material comprising a p-type semiconductor;

a second contact;

the magnitude of the work function of the optically sensitive material being at least 0.4 eV greater than the magnitude of the work function of the second contact;

the optically sensitive material having an electron lifetime that is greater than the electron transit time from the first contact to the second contact when the bias is applied between the first contact and the second contact;

the n-type semiconductor providing injection of electrons and blocking the extraction of holes; and

the interface between the n-type semiconductor and the optically sensitive material providing a surface recombination velocity less than 1 cm/s.

12. The device of claim 11, wherein the n-type semiconductor comprises a material selected from the group consisting of TiO2, TiO2 that has been chemically reduced, TiO2 that has been oxidized, CdTe, CdS, CdSe, Si, or nanoparticles selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, Si, Ge, or C.

13. The device of claim 11, wherein the bias is in the range of about −

0.1 Volts to −

2.8 Volts.

14. The device of claim 11, wherein the optically sensitive material comprises a plurality of nanoparticles, wherein each of the nanoparticles has an oxide on a surface of the respective nanoparticle.

15. The device of claim 11, wherein the optically sensitive material comprises nanoparticles selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, Si, Ge, or C.

16. The device of claim 11, wherein the optically sensitive material comprises a plurality of interconnected nanoparticles.

17. The device of claim 11, wherein the first contact and the second contact are separated by a distance in the range of 200 nm to 2 um.

18. The device of claim 11, wherein the first contact and the second contact each comprise a material selected from the group consisting of Al, Ag, In, Mg, Ca, Li, Cu, Ni, NiS, TiN, TaN, TiO2, TixNy, ITO, Ru, TiSi, WSi2, TiOx doped with B, TiOx doped with C, TiOx doped with Co, TiOx doped with Fe, TiOx doped with Nd, TiOx doped with N.

19. A photodetector comprising:

a first contact and a second contact, each having a work function;

an optically sensitive material between the first contact and the second contact, the optically sensitive material comprising a p-type semiconductor, and the optically sensitive material having a work function;

circuitry configured to apply a bias voltage between the first contact and the second contact;

the magnitude of the work function of the optically sensitive material being at least 0.4 eV greater than the magnitude of the work function of the first contact, and also at least 0.4 eV greater than the magnitude of the work function of the second contact;

circuitry configured to apply a bias voltage between the first contact and the second contact; and

the optically sensitive material configured to provide a responsivity of at least 0.8 A/W when the bias is applied between the first contact and the second contact.

20. The device of claim 19, wherein the work function of the first contact and the second contact are each shallower than 4.5 eV.

21. The device of claim 19, wherein the bias is in the range of about −

0.1 Volts to −

2.8 Volts.

22. The device of claim 19, wherein the optically sensitive material comprises nanoparticles selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, Si, Ge, or C.

23. The device of claim 22, wherein the optically sensitive layer further comprises a material selected from the group consisting of PbSO4, PbO, PbSeO4, PbTeO4, SiOxNy, In2O3, sulfur, sulfates, sulfoxides, carbon and carbonates.

24. The device of claim 19, wherein the first contact and the second contact each comprise a material selected from the group consisting of Al, Ag, In, Mg, Ca, Li, Cu, Ni, NiS, TiN, TaN, TiO2, TixNy, ITO, Ru, TiSi, WSi2, TiOx doped with B, TiOx doped with C, TiOx doped with Co, TiOx doped with Fe, TiOx doped with Nd, TiOx doped with N.

25. The device of claim 19, wherein the first contact and the second contact are separated by a distance in the range of 200 nm to 2 um and the electron mobility in the optically sensitive material is at least 1 E-5 cm2/Vs.