Skip to main content
Account

Table 4 Differences between top–down and bottom–up approach synthesis of SiNWs

From: Recent Advances in Silicon Nanowire Biosensors: Synthesis Methods, Properties, and Applications

 

Top–down approach

Bottom–up approach

Device preparation

SiNW and device development were done by etching a silicon-on-insulator (SOI) wafer.

SiNWs are produced from molecular precursors by using a metal nano-cluster mediated VLS mechanism.

Fabrication techniques are developed from technology like optical lithography, reactive ion etching, e-beam lithography, and anisotropic wet etching

For a transmission electron microscope (TEM) image, check Fig. 5b.

For a scanning electron microscope (SEM) image, check Fig. 5c.

 

Merits

Docile to mass production

Easiness in the choice of material for nanowire development

Alignment and directional control of the growth of nanowire crystal is possible [33].

Dependability and reproducibility of the synthesizing process

Various doping levels and high availability of dopants can be introduced during the synthesis.

No integration problems

There is high possibility of synthesizing SiNWs of diameter less than 10 nm.

SiNWs with several cross sections like triangular [34] and trapezoidal can be fabricated as its essential for selective functionalization of SiNWs [35].

Appropriate for fabricating multilayer SiNW device structures

SiNWs with double-gate structures that are reinforced on a co-planar geometry can be produced (improved sensitivity) [36, 37].

Flexible to incorporation with flexible and transparent device substrates [38]

Demerits

Demands a lot of time for processing

Leads to distribution of lengths and measurements of the synthesized SiNWs

Costly

Device development involves precise arrangement and positioning of SiNWs resulting to integration problems.

Restricted choice of materials for SiNW fabrication

Extremely hard to realize accurate control of number of SiNWs bridging the source and drain electrodes resulting to disparities in batch-to-batch fabrication of SiNW devices

Incompatibility of surface chemistry with the tough processing of nanofabrication

Alignment problems related with long SiNWs

Measurements of SiNWs restricted by the resolution of the fabrication process

Mass production of SiNW devices almost impossible

Navigation