# US 7,407,872 B2 · Epitaxial growth of aligned AlGalnN nanowires by metal-organic chemical vapor deposition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,872 B2 - Document ID: US7407872B2 - Status: Granted - Kind: B2 - Application number: 11/207,226 - Filed: 2005-08-19 - Published: 2006-04-06 - Granted: 2008-08-05 - Earliest claimed: 2004-08-20 - Assignees: Yale University - Inventors: Jung Han; Jie Su - Web page: https://patentgrep.com/patent/US7407872B2 ## CPC - H10P 14/274: {using seed materials} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - H10D 62/118: {Nanostructure semiconductor bodies} - H10D 62/121: {oriented parallel to substrates} - H10D 62/122: {oriented at angles to substrates, e.g. perpendicular to substrates} - H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN} - H10P 14/24: using chemical vapour deposition [CVD] - H10P 14/271: {characterised by the preparation of substrate for selective deposition} - H10P 14/279: {Vapour-liquid-solid growth} - H10P 14/2901: {Materials} - H10P 14/3416: {Nitrides} - H10P 14/3462: {Nanowires} - H10P 14/3216: {Nitrides} - H10P 14/3258: {Crystal orientation} - Y10S 977/763: formed along or from crystallographic terraces or ridges - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract Highly ordered and aligned epitaxy of III-Nitride nanowires is demonstrated in this work. <1010> M-axis is identified as a preferential nanowire growth direction through a detailed study of GaN/AlN trunk/branch nanostructures by transmission electron microscopy. Crystallographic selectivity can be used to achieve spatial and orientational control of nanowire growth. Vertically aligned (Al)GaN nanowires are prepared on M-plane AlN substrates. Horizontally ordered nanowires, extending from the M-plane sidewalls of GaN hexagonal mesas or islands demonstrate new opportunities for self-aligned nanowire devices, interconnects, and networks. ## Claims ### Claim 1 A method of growing nanowires in a selected growth direction, comprising the steps of: providing a substrate on which semiconductor islands or mesas are capable of being formed; forming semiconductor islands or mesas on a surface of the substrate by growing the islands or mesas on the surface of the substrate using metalorganic chemical vapor deposition (MOCVD); activating exposed surfaces of the islands or mesas to prepare the islands or mesas for the growth of nanowires thereon; and growing at least one nanowire in a selected growth direction from the activated surfaces of the islands or mesas. ### Claim 2 (depends on 1) The method according to claim 1, wherein the substrate is selected from the group consisting of sapphire, silicon carbide, aluminum nitride, and silicon. ### Claim 3 (depends on 2) The method according to claim 2, wherein the substrate is sapphire. ### Claim 4 (depends on 2) The method according to claim 2, wherein the substrate is silicon. ### Claim 5 (depends on 1) The method according to claim 1, wherein the islands or mesas exhibit 6-fold symmetry and have planes that are capable of growing nanowires thereon, said planes comprising a <1010> plane and a <1122> plane. ### Claim 6 (depends on 5) The method according to claim 5, wherein the islands or mesas are selected from the group consisting of gallium nitride and aluminum gallium nitride. ### Claim 7 (depends on 6) The method according to claim 6, wherein the islands are gallium nitride. ### Claim 8 (depends on 6) The method according to claim 6 wherein the nanowires are grown in a reactor epitaxially ante activated surfaces of the mesas or islands using MOCVD. ### Claim 9 (depends on 8) The method according to claim 8, wherein the nanowires are grown on the <1010> and/or the <1122> planes of the gallium nitride mesas or islands. ### Claim 10 (depends on 9) The method according to claim 9, wherein the nanowires do not grow on a <0001> plane of the gallium nitride mesas or islands. ### Claim 11 (depends on 8) The method according to claim 8, wherein the reactor is charged with a gallium precursor, a nitrogen precursor, and optionally, an aluminum and/or an indium precursor. ### Claim 12 (depends on 1) The method according to claim 1, wherein MOCVD is performed in a horizontal reactor at a temperature of about 1000-1000° C. and a pressure of about 200 mbar to atmospheric pressure. ### Claim 13 (depends on 12) The method according to claim 12, wherein the reactor is charged with a gallium precursor and a nitrogen precursor. ### Claim 14 (depends on 13) The method according to claim 13, wherein the gallium precursor is trimethylgallium and the nitrogen precursor is ammonia. ### Claim 15 (depends on 14) The method according to claim 14, wherein the ammonia is charged to the reactor at a rate of about 1-3 standard liters per minute. ### Claim 16 (depends on 1) The method according to claim 1, wherein the exposed surfaces of the islands or mesas are activated by coating the exposed surfaces of the islands or mesas with a catalytic metal selected from the group consisting of nickel, gold, and iron. ### Claim 17 (depends on 16) The method according to claim 16, wherein the catalytic metal is applied by electron beam metallization. ### Claim 18 (depends on 1) The method according to claim 1, wherein the nanowires are grown in a reactor epitaxially using metalorganic chemical vapor deposition (MOCVD), and wherein the reactor is maintained at a temperature of about 700-1000° C. and a pressure of about 20 mbar to atmospheric pressure. ### Claim 19 (depends on 18) The method according to claim 18, wherein the reactor is maintained at a temperature of about 900° C. ### Claim 20 (depends on 18) The method according to claim 18, wherein the reactor is maintained at a pressure of about 50 mbar. ### Claim 21 (depends on 18) The method according to claim 18, wherein the nanowires are selected from the group consisting of gallium nitride, aluminum gallium nitride, and indium gallium nitride. ### Claim 22 (depends on 18) The method according to claim 18, wherein the reactor is charged with a gallium precursor, a nitrogen precursor, and optionally, an aluminum and/or an indium precursor. ### Claim 23 (depends on 22) The method according to claim 22, further comprising a carrier gas that is nitrogen or a combination of nitrogen and hydrogen. ### Claim 24 A method of growing nanowires in a selected growth direction, comprising the steps of: providing a substrate on which semiconductor islands or mesas are capable of being formed; forming semiconductor islands or mesas on a surface of the substrate, wherein the islands or mesas are selected from the group consisting of gallium nitride and aluminum gallium nitride; activating exposed surfaces of the islands or mesas to prepare the islands or mesas for the growth of nanowires thereon; and growing at least one nanowire in a selected growth direction from the activated surfaces of the islands or mesas. ### Claim 25 A method of growing nanowires in a selected growth direction, comprising the steps of: providing a substrate on which semiconductor islands or mesas are capable of being formed; forming semiconductor islands or mesas on a surface of the substrate, wherein the islands or mesas are formed so that sidewalls of the islands or mesas are pyramidal; activating exposed surfaces bf the islands or mesas to prepare the islands or mesas for the growth of nanowires thereon; and growing at least one nanowire in a selected growth direction from the activated surfaces of the islands or mesas.