The fabrication of 3D nanostructures can be achieved through several methods:
1. Top-Down Approaches: Techniques such as lithography and etching are used to carve out nanostructures from bulk materials.
2. Bottom-Up Approaches: These involve the assembly of nanostructures from atomic or molecular components. Examples include chemical vapor deposition (CVD), molecular self-assembly, and sol-gel processes.
3. Hybrid Approaches: Combining top-down and bottom-up methods to achieve complex architectures that are otherwise difficult to fabricate by a single technique.
