Metal based nanowire tunnel junctions
Semiconductor light emitting diodes (LEDs) formed as (Al)GaN-based nanowire structures have a first semiconductor layer, a second semiconductor layer, and a thin metallic layer fabricated therebetween. The structures, operating in the deep ultraviolet (UV) spectral range, exhibit high photoluminescence efficiency at room temperature. The structures may be formed of an epitaxial metal tunnel junction operating as a reflector that enhances carrier transport to and from the semiconductor alloy layers, capable of producing external quantum efficiencies at least one order of magnitude higher than convention devices.
1. A semiconductor emitter comprising:
a tunnel junction comprising a metallic layer disposed between a first semiconductor alloy and a second semiconductor alloy; wherein the metallic layer also acts as a reflector within the semiconductor emitter, wherein the semiconductor emitter is a nanowire and the tunnel junction is part of the nanowire.
2. A semiconductor device comprising a tunnel junction comprising a first semiconductor alloy of a first composition, and a layer of a metal of a second composition, wherein the semiconductor device is a nanowire.
3. The semiconductor device according to claim 2 , wherein the layer of the metal enhances carrier transport to and from at least one of the first semiconductor alloy and a second semiconductor alloy.
4. The semiconductor device according to claim 3 , wherein the first semiconductor alloy is n++-GaN; the second semiconductor alloy is p++-GaN; and the layer of the metal is a metallic layer comprising Al.
5. The semiconductor device according to claim 2 , wherein the layer of the metal forms at least one of a quasi-ohmic contact and an ohmic contact with at least one of the first semiconductor alloy and a second semiconductor alloy.
6. The semiconductor device according to claim 5 , wherein the layer of metal is positioned in the semiconductor device to form semiconductor/metal/semiconductor epitaxial layers exhibiting quasi-ohmic or ohmic contact characteristics and to enable efficient inter-band conduction from a first p-type semiconductor alloy to a second n-type semiconductor alloy, through the layer of metal.
7. The semiconductor device according to claim 6 , wherein the layer of metal is an Al layer interconnect, the first p-type semiconductor alloy is a p++-GaN alloy, the second n-type semiconductor alloy is a n++-GaN alloy, and the semiconductor/metal/semiconductor epitaxial layers are n++-GaN/Al/p++-GaN epitaxial layers.
8. The semiconductor device according to claim 2 , wherein the layer of metal is a metallic layer configured to provide an optical reflector for photons emitted from the semiconductor device.
9. A semiconductor device comprising:
a plurality of semiconductor layers, each semiconductor layer of the plurality of semiconductor layers having a composition; and
a plurality of metallic layers, each metallic layer of the plurality of metallic layers comprising a metal and disposed between a pair of semiconductor layers of the plurality of semiconductor layers, wherein a metallic layer of the plurality of metallic layers in combination with its associated pair of semiconductor layers of the plurality of semiconductor layers comprises a tunnel junction, and wherein the semiconductor device comprises a plurality of nanowires.
10. The semiconductor device according to claim 9 , wherein a portion of the semiconductor device is configured to be optically pumped.
11. The semiconductor device according to claim 9 , wherein a semiconductor layer of the plurality of semiconductor layers further comprises a quantum structure.
12. A device comprising:
a substrate;
a first metallic layer disposed on a surface of the substrate; and
a semiconductor device comprising a plurality of nanowires disposed at locations on the substrate, the locations defined by openings within the first metallic layer, wherein the first metallic layer acts as an optical reflector for the semiconductor device, wherein the plurality of nanowires comprise a nanowire comprising a tunnel junction, and wherein the tunnel junction comprises a second metallic layer disposed between a first semiconductor alloy and a second semiconductor alloy.
13. The device according to claim 12 , wherein the semiconductor device is a type of device selected from the group consisting of: an optical emitter, a photodetector, and a solar cell.