Hydrogen diffusion barrier for hybrid semiconductor growth
Semiconductor devices and methods of fabricating semiconductor devices having a dilute nitride active layer and at least one semiconductor material overlying the dilute nitride active layer are disclosed. Hybrid epitaxial growth and the use of hydrogen diffusion barrier layers to minimize hydrogen diffusion into the dilute nitride active layer are used to fabricate high-efficiency multijunction solar cells and photonic devices. Hydrogen diffusion barriers can be formed through the use of layer thickness, composition, doping and/or strain.
1. A semiconductor device comprising:
a dilute nitride active layer, wherein the dilute nitride active layer comprises:
a dilute nitride material selected from GaNAs, GaInNAs, GaInNAsSb, GaInNAsBi, GaInNAsSbBi, GaNAsSb, GaNAsBi, and GaNAsSbBi;
a background doping concentration less than 5×10 16 cm −3 ; and
a hydrogen-induced defect density less than the background doping density;
a hydrogen diffusion barrier region overlying the dilute nitride active layer, wherein the hydrogen diffusion barrier region comprises a doped semiconductor layer, a dilute nitride semiconductor layer, a strained semiconductor layer, or a combination of any of the foregoing; and
one or more semiconductor layers overlying the hydrogen diffusion barrier region.
2. The semiconductor device of claim 1 , wherein the hydrogen diffusion barrier region is adjacent the dilute nitride active layer, without any intervening semiconductor layers.
3. The semiconductor device of claim 1 , wherein the hydrogen diffusion barrier region comprises a doped semiconductor layer.
4. The semiconductor device of claim 3 , wherein the doped semiconductor layer comprises a dopant selected from C, Be, Zn, Si, Se, Te, and a combination of any of the foregoing.
5. The semiconductor device of claim 3 , wherein the doped semiconductor layer comprises a doping level between 1×10 17 cm −3 and 2×10 20 cm −3 .
6. The semiconductor device of claim 1 , wherein the hydrogen diffusion barrier region comprises a dilute nitride semiconductor layer.
7. The semiconductor device of claim 6 , wherein,
the dilute nitride active layer comprises a first bandgap;
the dilute nitride semiconductor layer comprises a second bandgap; and
the second bandgap is larger than the first bandgap.
8. The semiconductor device of claim 6 , wherein the dilute nitride semiconductor layer comprises GaAsN, AlGaAsN, GaInAsN, GaN, AlN, AlNSb, GaNSb, GaInNAsSb, GaNBi or AlNBi.
9. The semiconductor device of claim 1 , wherein the hydrogen diffusion barrier region comprises a strained semiconductor layer.
10. The semiconductor device of claim 9 , wherein,
the semiconductor device further comprises a substrate underlying the dilute nitride active layer; and
the strained semiconductor layer has strain within a range from +/−3.5% with respect to the substrate.
11. The semiconductor device of claim 9 , wherein the strained semiconductor layer is a strained superlattice structure (SLS).
12. The semiconductor device of claim 1 , wherein the hydrogen diffusion barrier region does not contain aluminum.
13. The semiconductor device of claim 1 , wherein each of the dilute nitride active layer and the hydrogen diffusion barrier region is grown by molecular beam epitaxy.
14. The semiconductor device of claim 1 , wherein the semiconductor layer adjacent the hydrogen diffusion barrier region is grown by MOCVD.
15. The semiconductor device of claim 1 , further comprising a hydrogen diffusion barrier region underlying the dilute nitride active layer.
16. The semiconductor device of claim 1 , wherein the semiconductor device comprises a solar cell, a vertical cavity surface emitting laser, a resonant cavity enhanced photodetector, an edge-emitting laser, a light emitting diode, a photodetector, an avalanche photodetector, or an optoelectronic modulator.