Nanowire heterostructures and methods of forming the same

A method for performing NERS comprising:

• providing a NERS-active structure comprising:
• at least one heterostructure nanowire comprising:
• at least two active regions;
• and
• at least one inactive region between the at least two active regions;
• placing an analyte adjacent to the NERS-active structure;
• irradiating the analyte and the NERS-active structure with excitation radiation;
• and
• detecting Raman scattered radiation scattered by the analyte.

A method for forming a NERS-active structure, comprising:

• providing a substrate;
• providing at least one catalyst nanoparticle;
• exposing the at least one catalyst nanoparticle to a gas comprising a first material to promote the formation of at least one nanowire of the first material;
• and
• exposing the at least one catalyst nanoparticle and the at least one nanowire to a gas comprising a second material to promote the formation of a heterostructure nanowire of the first material and the second material, wherein one of the first material and the second material comprises a NERS-active material and one of the first material and the second material comprises an NERS-inactive material.

A method for forming a NERS-active structure, comprising:

• providing a substrate;
• growing at least one nanowire of a first material on the substrate;
• coating the at least one nanowire with a second material to form at least one coated nanowire;
• coating the at least one coated nanowire with the first material to form at least one radial core-shell nanowire;
• embedding the at least one radial core-shell nanowire in a support matrix;
• and
• polishing the at least one radial core-shell nanowire and the support matrix to expose at least one multilayer ring.