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;
a dilute nitride active region overlying the first doped region, wherein the dilute nitride active region comprises either:
a single layer active region comprising a first portion and a second portion, wherein the first portion has a higher bandgap than the second portion, or
a multiple layer active region comprising a first layer and a second layer, wherein the first layer has a higher bandgap than the second layer; and
a second doped region overlying the dilute nitride active region.
2 . The compound semiconductor optoelectronic structure of claim 1 , wherein:
a first thickness of the first portion is different from a second thickness of the second portion, or
a first thickness of the first layer is different from a second thickness of the second layer.
3 . The compound semiconductor optoelectronic structure of claim 1 , wherein the multiple layer active region comprises n active layers having bandgaps that increase or decrease monotonically.
4 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride active region comprises GaInNAsSb.
5 . The compound semiconductor optoelectronic structure of claim 1 , wherein a bandgap difference between a highest bandgap and a lowest bandgap of the portions or the layers in the dilute nitride active region is at least 40 meV.
6 . The compound semiconductor optoelectronic structure of claim 1 , wherein a bandgap difference between a highest bandgap and a lowest bandgap of the portions or the layers in the dilute nitride active region is less than 700 meV.
7 . The compound semiconductor optoelectronic structure of claim 1 , wherein the first layer has a first bandgap and a first thickness and the second layer has a second bandgap and a second thickness, wherein the second bandgap is greater than the first bandgap and the second thickness is greater than the first thickness,
wherein the multiple layer active region further comprises a third layer having a third bandgap and a third thickness, wherein the third bandgap is greater than the second bandgap, and the third thickness is greater than the second thickness.
8 . The compound semiconductor optoelectronic structure of claim 1 , further comprising a reflector underlying the dilute nitride active region.
9 . The compound semiconductor optoelectronic structure of claim 1 , wherein the first layer has a first bandgap of 0.85 eV, and the second layer has a second bandgap of 0.76 eV.
10 . The compound semiconductor optoelectronic structure of claim 1 , wherein the bandgaps of the dilute nitride active region are within a range from 0.7 eV to 1.4 eV.
11 . The compound semiconductor optoelectronic structure of claim 1 , wherein thicknesses of the portions or the layers in the dilute nitride active region is within a range from 0.2 μm to 10 μm.
12 . The compound semiconductor optoelectronic structure of claim 1 , wherein a bandgap of the dilute nitride active region varies continuously, linearly, quadratically, or exponentially throughout a thickness of the dilute nitride active region.
13 . The compound semiconductor optoelectronic structure of claim 1 , wherein at least one of the first portion or the second portion has a uniform bandgap, or at least one of the first layer or the second layer has a uniform bandgap.
14 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride active region comprises GaInNAs, GaNAsSb, GaInNAsSb, GaInNAsBi, GaNAsSbBi, GaNAsBi, GaInNAsSbBi, or a combination thereof.
15 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride action region comprises Ga 1-x In x N y As 1-y-z Sb z , wherein:
0≤x≤0.4, 0≤y≤0.07, and 0≤z≤0.04;
0.12≤x≤0.24, 0.03≤y≤0.07, and 0.001≤z≤0.02;
0.12≤x≤0.24, 0.03≤y≤0.07, and 0.005≤z≤0.04;
0.13≤x≤0.20, 0.03≤y≤0.045, and 0.001≤z≤0.02;
0.13≤x≤0.18, 0.03≤y≤0.04, and 0.001≤z≤0.02; or
0.18≤x≤0.24, 0.04≤y≤0.07, and 0.001≤z≤0.04.
16 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride action region comprises an intentionally doped active layer, the intentionally doped active layer comprising a constant doping profile, a discontinuous doping profile, or a continuous doping profile.
17 . The compound semiconductor optoelectronic structure of claim 1 , wherein the first portion is closer to the substrate than the second portion, or the first layer is closer to the substrate than the second layer.
18 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride active region comprises a dilute nitride material having a compressive strain within a range from 0% to 0.4% with respect to the substrate.
19 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride active region has a lattice constant that is less than 3% the lattice constant of GaAs or Ge.
20 . The compound semiconductor optoelectronic structure of claim 1 , wherein the dilute nitride active region comprises a dilute nitride material having a photoluminescence full-width half-maximum (FWHM) from 50 nm to 150 nm as determined using photoluminescence spectroscopy.