Self-assembled monolayers on solid substrates Directed assembly of micro- and nano-structures

1 self-assembled monolayers on solid substrates

1.1 acoustic methods
1.2 optical methods
1.3 magnetic methods
1.4 dielectrophoretic methods

self-assembled monolayers on solid substrates

self-assembled monolayers (sams) made of layer of organic molecules forms naturally ordered lattice on surface of desired substrate. molecules in lattice have connections chemically @ 1 end (head group), while other end (end group) creates exposed surface of sam.

many types of sams can formed. example: thiols form sams on gold, silver, copper, or on compound semiconductors such inp , gaas. changing tail group of molecules, different surface properties can obtained; therefore sams can used render surfaces hydrophobic or hydrophilic change surface states of semiconductor. self-assembly, positioning of sams used define chemical system precisely find target location in molecular-inorganic device. characteristic, sams candidates molecular electronic devices such use sams build electronic devices , maybe circuits intriguing prospect. because of ability provide basis high-density data storage , high-speed devices.

acoustic methods

directed assembly using acoustic methods manipulate waves in order allow non-invasive assembling of micro , nano structures. due this, acoustics used in biomedical industry manipulate droplets, cells , other molecules.

acoustic waves generated piezoelectric transducer controlled pulse generator. these waves able manipulate droplets of liquid , move them together, in order form packed assembly. moreover, frequency , amplitude of waves can modified in order achieve more accurate control of particular behavior of droplet or cell.

optical methods

directed assembly or more directed self-assembly, can produce high pattern resolution (~10 nm) high efficiency , compatibility. however, when using dsa in high volume manufacturing, 1 must have way quantify degree of order of line/space patterns formed dsa in order reduce defect.

normal approach such critical dimension-scanning electron microscopy (cd-sem) obtain data pattern quality inspection takes time , labor-intensive. on other hand, optical scatterometer-based metrology non-invasive technique , has high throughput due larger spot size. these results in collection of more statistical data using sem, , data processing automated optical technique making more feasible traditional cd-sem.

magnetic methods

magnetic field directed self-assembly (mfdsa) allows manipulation of dispersion , subsequent assembly of magnetic nanoparticles. used in development of advanced materials whereby inorganic nanoparticles (nps) dispersed in polymers, in order enhance properties of materials.

the magnetic field technique allows assembling of particles in 3d doing assembly in dilute suspension solvent not evaporate. not need use template, , approach improve magnetic anisotropy along chain direction.

dielectrophoretic methods

dielectrophoretic directed self-assembly utilizes electric field controls metal particles, such gold nanorods, inducing dipole in particles. varying polarity , strength of electric field, polarized particles either attracted positive regions or repelled negative regions electric field has higher strength. direct manipulation method transports particles position , orient them nano-structure on receptor substrate.