Thin-walled structures
Various embodiments provide thin-walled structures and methodologies for their formation. In one embodiment, the thin-walled structure can be formed by disposing a semiconductor material in a patterned aperture using a selective growth mask that includes a plurality of patterned apertures, followed by a continuous growth of the semiconductor material using a pulsed growth mode. The patterned aperture can include at least one lateral dimension that is small enough to allow a threading defect termination at sidewall(s) of the formed thin-walled structure. In addition, high-quality III-N substrate structures and core-shell MQW active structures can be formed from the thin-walled structures for use in devices like light emitting diodes (LEDs), lasers, or high electron mobility transistors (HEMTs).
1. A method of forming a thin-walled structure comprising:
forming a selective growth mask over a substrate, wherein the selective growth mask comprises a plurality of patterned apertures;
forming a thin-walled structure on the substrate by disposing a semiconductor material in each patterned aperture using a non-pulsed growth mode; and
growing the thin-walled structure using a pulsed growth mode of the semiconductor material, wherein the thin-walled structure comprises a hollow shape having a wall thickness.
2. The method of claim 1 , wherein at least one lateral dimension of each patterned aperture is about 1 micron or less.
3. The method of claim 1 , wherein at least one lateral dimension of each patterned aperture is about 500 nm or less to form a thin-walled nanowire structure.
4. The method of claim 1 , wherein the thin-walled structure has a length of about 1 micron to about 10 mm.
5. The method of claim 1 , wherein the wall thickness is about 1000 nm or less.
6. The method of claim 1 , wherein the thin-walled structure comprises a thin-walled hollow structure having a lateral cross section selected from the group consisting of a thin-walled polygon, a thin-walled rectangle, a thin-walled square, a thin-walled oval, and a thin-walled circle.
7. The method of claim 1 , wherein the substrate comprises one or more materials selected from the group consisting of Si, SiC, sapphire, GaN and GaAs.
8. The method of claim 1 , wherein the pulsed growth mode is applied before or after growth of the semiconductor material protrudes over a top of the selective growth mask.
9. The method of claim 1 , wherein the semiconductor material for forming the thin-walled structure comprises one or more materials selected from the group consisting of GaN, AlN, InN, InGaN, AlInGaN and AlGaN.
10. A group III-N thin-walled structure formed according to the method of claim 1 .
11. The method of claim 1 , further comprising forming a group III-N substrate structure by terminating and coalescing one or more formed thin-walled structures.
12. The method of claim 1 , further comprising forming a multiple quantum well (MOW) active structure on one or more sidewalls of the formed thin-walled structure, the thin-walled structure being used as a core structure.
13. A group III-N substrate structure formed by the method of claim 11 .
14. The method of claim 12 , wherein the MOW active structure comprises one or more materials chosen from AlGaN, InGaN, AlInGaN, GaN, AlN, and InN.
15. A thin-walled structure comprising:
a selective growth mask disposed over a substrate, wherein the selective growth mask comprises a plurality of patterned apertures with each patterned aperture exposing a surface portion of the substrate; and
a thin-walled structure connected to and extending from the surface portion of the substrate and through each patterned aperture, wherein the thin-walled structure comprises a hollow shape having a wall thickness of 1000 nm or less.
16. The structure of claim 15 , wherein the at least one lateral dimension of each patterned aperture is about 1 micron or less.
17. The structure of claim 15 , wherein the at least one lateral dimension of each patterned aperture is about 500 nm or less for a thin-walled nanowire structure.
18. The structure of claim 15 , wherein the thin-walled structure has a length of about 1 micron or longer extended from the substrate surface.
19. The structure of claim 15 , wherein the thin-walled structure comprises a thin wall, a thin-walled polygon, a thin-walled rectangle, a thin-walled square, a thin-walled oval, or a thin-walled circle.
20. A multiple quantum well (MQW) active structure disposed on one or more sidewalls of the thin-walled structure of claim 15 , to form a core-shell active structure for a device comprising a light emitting diode (LED), a laser, or a high electron mobility transistor (HEMT).