Mid-infrared photodetectors
Nanoparticles, methods of manufacture, devices comprising the nanoparticles, methods of their manufacture, and methods of their use are provided herein. The nanoparticles and devices having photoabsorptions in the range of 1.7 μm to 12 μm and can be used as photoconductors, photodiodes, phototransistors, charge-coupled devices (CCD), luminescent probes, lasers, thermal imagers, night-vision systems, and/or photodetectors.
1. A method comprising:
reacting a mercury(II) salt in an oleylamine and elemental tellurium dissolved in a trialkylphosphine at a temperature in the range from 70 to 100° C., thereby forming HgTe nanoparticles; and
isolating the HgTe nanoparticles,
wherein the nanoparticles exhibit an absorption edge above 3 μm and a photoluminescence peak at a wavelength in a range of 1.7 μm to 12 μm.
2. The method of claim 1 , wherein the nanoparticles exhibit a photoluminescence peak at a frequency between 1.7 μm and 5 μm.
3. The method of claim 1 , wherein the nanoparticles exhibit an absorption edge at a wavelength in a range of 4 μm to 12 μm.
4. The method of claim 1 , wherein the tellurium is dissolved in a trioctylphosphine.
5. The method of claim 1 , wherein isolating the nanoparticles comprises admixing an alkane thiol with the nanoparticles thereby forming a quenched mixture; and then extracting the nanoparticles from the quenched mixture.
6. The method of claim 1 , wherein the nanoparticles comprise nanoparticles that exhibit an absorption edge at a wavelength in the range from beyond 3 μm up to about 5 μm.
7. The method of claim 1 , wherein the nanoparticles comprise nanoparticles that exhibit an absorption edge at a wavelength in the range from about 4 μm to about 5 μm.
8. A film of HgTe nanoparticle that exhibits an absorption edge above 3 μm at a temperature of 300 K, and a photoluminescence peak at a wavelength in a range from 2.5 μm to 12 μm.
9. A method comprising:
providing a first plurality of electrical connections; and
forming a first photoabsorptive layer that comprises the film of claim 8 , has a thickness in a range of 10 nm to 50 μm, and is in contact with the first plurality of electrical connections.
10. The method of claim 9 , wherein the HgTe nanoparticles exhibit a photoluminescence peak width at half height in a range of 300 to 1000 cm −1 .
11. The method of claim 9 , wherein the first photoabsorptive layer exhibits an absorption edge at a wavelength in a range from above 3 μm to 12 μm at a temperature of 300 K.
12. The method of claim 9 further comprising:
providing a second plurality of electrical connections; and
depositing HgTe nanoparticles as a second photoabsorptive layer in contact with the second plurality of electrical connections;
wherein the mean particle diameter of the HgTe nanoparticles in the second photoabsorptive layer differs from the mean particle diameter of the HgTe nanoparticles in the first photoabsorptive layer.
13. A photoconductor, photodiode, or phototransistor comprising:
a photoabsorptive layer comprising the film of claim 8 ; and
a first plurality of electrical connections bridging the photoabsorptive layer;
wherein the photoabsorptive layer, exhibits a photocurrent at a wavelength in the range of 3 μm to 12 μm at a temperature of 300 K.
14. A device comprising:
a plurality of the photoconductors, photodiodes, or phototransistors of claim 13 ; and
a readout circuit electrically connected to the plurality of the photoconductors, photodiodes, or phototransistors.
15. The device of claim 14 , wherein the plurality of photoconductors, photodiodes, or phototransistors comprises a first plurality of photoconductors, photodiodes, or phototransistors and a second plurality of photoconductors, photodiodes, or phototransistors; and wherein a photoluminescence peak frequency of the HgTe nanoparticles of the first plurality of photoconductors, photodiodes, or phototransistors is different from a photoluminescence peak frequency of the HgTe nanoparticles of the second plurality of photoconductors, photodiodes, or phototransistors.
16. The device of claim 14 , wherein the device is selected from the group consisting of a charged coupled device (CCD), a luminescent probe, a laser, a thermal imager, a night-vision system, and a photodetector.
17. The device of claim 14 , wherein the device is a charge-coupled device (CCD) photodetector and further comprising:
a first region that comprises a plurality of the first photoconductors, photodiodes, or phototransistors:
a second region that comprises a plurality of the second photoconductors, photodiodes, or phototransistors; and
a circuit for each region, each circuit including a cathode layer and an anode layer and further comprising a charge store and a readout circuit.
18. A method of producing an image comprising:
providing the device of claim 14 ;
exposing the device to light at wavelengths absorbed by the HgTe nanoparticles to provide a photoresponsive current; and
rendering the photoresponsive current as an image or image data file.
19. The film of claim 8 , wherein the film exhibits an absorption edge at a wavelength in the range from about 4 μm to about 5 μm at a temperature of 300 K.
20. The film of claim 19 , wherein the nanoparticles have a mean diameter in the range from about 10.5 to 13 nm.
21. The film of claim 8 , wherein the film exhibits an absorption edge at a wavelength of at least about 5 μm at a temperature of 300 K.
22. The film of claim 21 , wherein the nanoparticles have a mean diameter in the range from 10.5 to 13 nm.
23. The film of claim 8 , wherein the film exhibits a photocurrent across the wavelength range from 3 μm to 5 μm.