Short wavelength infrared optoelectronic devices having graded or stepped dilute nitride active regions
Semiconductor optoelectronic devices having a dilute nitride active region are disclosed. In particular, the semiconductor devices have a dilute nitride active region with at least two bandgaps within a range from 0.7 eV and 1.4 eV. Photodetectors comprising a dilute nitride active region with at least two bandgaps have a reduced dark current when compared to photodetectors comprising a dilute nitride active region with a single bandgap equivalent to the smallest bandgap of the at least two bandgaps.
1. A compound semiconductor optoelectronic structure, comprising:
a substrate having a substrate surface;
a first doped region overlying the substrate surface;
an active region overlying the first doped region, wherein the active region comprises:
a dilute nitride material; and
the active region has a bandgap that is non-uniform orthogonal to the substrate surface; and
a second doped region overlying the active region;
wherein the active region comprises two or more active layers; and
wherein at least one of the two or more active layers has a non-uniform bandgap.
2. The structure of claim 1 , wherein the bandgap is within a range from 0.7 eV to 1.4 eV.
3. The structure of claim 1 , wherein the bandgap varies continuously within at least a portion the thickness of the active region.
4. The structure of claim 1 , wherein the bandgap varies linearly throughout the thickness of the active region.
5. The structure of claim 1 , wherein the bandgap varies non-linearly throughout the thickness of the active region.
6. The structure of claim 1 , wherein the active region is intentionally doped.
7. The structure of claim 6 , wherein the intentionally doped active region comprises a constant doping profile, a discontinuous doping profile or a continuous doping profile.
8. The structure of claim 7 , wherein the discontinuous doping profile comprises a stepped doping profile.
9. The structure of claim 1 , wherein each of the two or more active layers comprises a dilute nitride material.
10. The structure of claim 1 , wherein each of the two or more active layers has a different bandgap than each of the other active layers.
11. The structure of claim 1 , wherein each of the two or more active layers independently comprises a uniform bandgap or a non-uniform bandgap.
12. The structure of claim 1 , wherein a bandgap difference between the lowest bandgap and the highest bandgap of the dilute nitride material within the active region is at least 40 meV.
13. The structure of claim 12 , wherein the bandgap difference is from 40 meV to 700 meV.
14. The structure of claim 1 , wherein the dilute nitride material comprises GaInNAs, GaNAsSb, GaInNAsSb, GaInNAsBi, GaNAsSbBi, GaNAsBi, GaInNAsSbBi, or a combination of any of the foregoing.
15. The structure of claim 1 , wherein the dilute nitride material has a photoluminescence full-width-half-maximum (FWHM) from 50 nm to 150 nm as determined using photoluminescence spectroscopy.
16. The structure of claim 1 , wherein an X-ray diffraction (XRD) pattern of the dilute nitride material exhibits a splitting from 300 arcsec to 1,000 arcsec.
17. The structure of claim 1 , wherein the dilute nitride material exhibits a carrier lifetime from 1.1 nanoseconds to 2.5 nanoseconds as measured at room temperature using an excitation wavelength of 970 nm, with an average CW power of 0.250 mW, and a pulse duration of 200 fs generated by a Ti:Sapphire:OPA laser with a pulse repetition rate of 250 kHz and a laser beam diameter at the sample of 1 mm.
18. The structure of claim 1 , wherein each of the first doped region and the second doped region independently has a bandgap that is greater than the largest bandgap of a material within the active region.
19. A device comprising the structure of claim 1 .
20. The device of claim 19 , wherein the device comprises a plurality of the semiconductor structures of claim 1 .
21. The device of claim 19 , wherein the device comprises a photodetector.
22. The device of claim 19 , wherein the device comprises a photodetector array.
23. A method of forming a semiconductor optoelectronic device, comprising:
forming a first doped region overlying a substrate having a surface;
forming an active region overlying the first doped region, wherein,
the active region comprises a dilute nitride material; and
the active region has a bandgap that is non-uniform orthogonal to the substrate surface; and
forming a second doped region overlying the active region;
wherein the active region comprises two or more active layers; and
wherein at least one of the two or more active layers has a non-uniform bandgap.
24. The method of claim 23 , wherein the device comprises a photodetector.
25. A semiconductor optoelectronic device fabricated using the method of claim 23 .
26. The semiconductor optoelectronic device of claim 25 , wherein the device comprises a photodetector.
27. The semiconductor optoelectronic device of claim 25 , wherein the device comprises a photodetector array.
28. The semiconductor optoelectronic device of claim 25 , wherein,
the active region has a minimum bandgap; and
the device has a dark current, wherein the dark current less than a dark current of a device having the same structure except that the active region has a constant bandgap that is equivalent to the minimum bandgap.
29. The semiconductor optoelectronic device of claim 25 , wherein,
the active region has a minimum bandgap; and
the device has a signal-to-noise ratio, wherein the signal-to-noise ratio is higher than a signal-to-noise ratio of a device having the same structure except that the active region has a constant bandgap that is equivalent to the minimum bandgap.