Device with nitride nanowires having a shell layer and a continuous layer
View Patent ↗The present invention relates to the growing of nitride semiconductors, applicable for a multitude of semiconductor devices such as diodes, LEDs and transistors. According to the method of the invention nitride semiconductor nanowires are grown utilizing a CVD based selective area growth technique. A nitrogen source and a metal-organic source are present during the nanowire growth step and at least the nitrogen source flow rate is continuous during the nanowire growth step. The V/III-ratio utilized in the inventive method is significantly lower than the V/III-ratios commonly associated with the growth of nitride based semiconductor.
1. A light emitting diode (LED), comprising:
a plurality of Group III-nitride nanowires extending from a substrate;
at least one Group III-nitride shell layer located on each of the plurality of Group III-nitride nanowires; and
a continuous Group III-nitride layer located over the at least one Group III-nitride shell layer on each of the plurality of Group III-nitride nanowires, the continuous Group III-nitride layer continuously covering all of the plurality of Group III-nitride nanowires;
wherein:
the at least one Group III-nitride shell layer comprises an active region of the LED;
the plurality of Group III-nitride nanowires are doped one of n- or p-type;
the continuous Group III-nitride layer is doped another one of p- or n-type to form a junction with the plurality of Group III-nitride nanowires;
the plurality of Group III-nitride nanowires are grown by a chemical vapor deposition (CVD) based selective growth area technique;
the plurality of Group III-nitride nanowires extend from the substrate through openings in a growth mask layer located over the substrate;
each of the plurality of Group III-nitride nanowires comprises a rod shaped lower portion and a pyramidal shaped cap portion above the rod shaped lower portion; and
the rod shaped lower portion contains vertical facets of a (1100) plane which extend above an upper surface of the growth mask layer.
2. The LED of claim 1 , wherein a p-n junction is provided by each individual Group III-nitride nanowire combined with the continuous Group III-nitride layer.
3. The LED of claim 1 , wherein a molar V/III-ratio during growth of the at least one Group III-nitride shell layer is higher than a molar V/III-ratio during growth of the plurality of Group III-nitride nanowires.
4. The LED of claim 3 , wherein the plurality of Group III-nitride nanowires comprise a plurality of substantially defect free Group III-nitride nanowires and wherein at least 90% of the plurality of Group III-nitride nanowires have a same crystal structure through their respective entire lengths.
5. The LED of claim 4 , wherein the plurality of Group III-nitride nanowires comprise GaN nanowires.
6. The LED of claim 5 , wherein the at least one Group III-nitride shell layer comprises an InGaN shell layer.
7. The LED of claim 1 , wherein the rod shaped lower portion directly above the growth mask layer has about a same width as the openings in the growth mask layer through which the plurality of Group III-nitride nanowires extend.
8. The LED of claim 7 , wherein the growth mask layer comprises an insulating layer.
9. The LED of claim 8 , wherein the growth mask layer comprises SiN x or SiO x .
10. The LED of claim 7 , wherein the plurality of Group III-nitride nanowires each have a diameter between 50 nm and 500 nm.