Porous wire-in-tube structures

A system for fabricating porous wire-in-tube (WiT) nanostructures, the system comprising:

• a main chamber, comprising:
• a substrate holding a semi-conductive core, the semi-conductive core comprising at least one of a silicon core and a germanium core;
• and
• a pair of parallel metal electrodes, comprising:
• a top electrode configured to generate a plurality of metal particles, the top electrode comprising at least one of an aluminum (Al) electrode and a titanium (Ti) electrode;
• and
• a ground electrode configured to hold the substrate;
• and
• a gas source of a plurality of gas sources, the gas source configured to contain at least one gas of a plurality of gases, the plurality of gases comprising O2, H2, and a fluorine-containing gas, the fluorine-containing comprising sulfur hexafluoride (SF6);
• a gas inlet configured to introduce a mixture of the plurality of gases into the main chamber;
• a gas valve of a plurality of gas valves, the gas valve configured to couple the gas inlet with a respective gas source of the plurality of gas sources;
• a vacuum pump configured to generate a vacuum inside the main chamber;
• and
• a radiofrequency generator configured to generate a plasma environment with a plasma power between 100 W and 300 W in the vacuum;
• a memory having processor-readable instructions stored therein;
• and
• one or more processors configured to access the memory and execute the processor-readable instructions, which, when executed by the one or more processors configures the one or more processors to perform a method, the method comprising:
• forming a first porous core-shell nanostructure, forming the first porous core-shell nanostructure comprising:
• forming a porous layer on a semi-conductive core by depositing a first plurality of particles on the semi-conductive core, forming the porous layer comprising obtaining a plurality of unmasked regions, each of the plurality of unmasked regions comprising a portion of a surface of the semi-conductive core, the surface not covered with one or more of the first plurality of particles;
• and
• generating an initial porous semi-conductive core by etching the plurality of unmasked regions of the semi-conductive core simultaneously with forming the porous layer;
• forming a second porous core-shell nanostructure comprising increasing thickness and porosity of the first porous core-shell nanostructure by repeating an iterative process until the thickness of the porous layer reaches a predefined threshold, the iterative process comprising:
• increasing the thickness of the porous layer by depositing a second plurality of particles on the semi-conductive core;
• and
• generating a secondary porous semi-conductive core by etching the plurality of unmasked regions of the semi-conductive core simultaneously with depositing the second plurality of particles;
• and
• forming a porous WiT nanostructure by etching the secondary porous semi-conductive core.

A wire-in-tube nanostructure, comprising:

• a porous nanotube;
• a semi-conductive nanowire enclosed within the porous nanotube;
• and
• a gap between the porous nanotube and the semi-conductive nanowire.