Carbon nanotechnology

Smoltek’s patent-pro­tect­ed tech­nol­o­gy plat­form enables con­trolled growth of pre­cise­ly local­ized and defined nanos­truc­tures, as indi­vid­ual fibers or clus­ters, in pre­de­fined pat­terns or films. This is done in a through cat­alyt­ic growth in a vac­u­um cham­ber using gas and cat­a­lysts. Mate­ri­als and process con­di­tions are com­pat­i­ble with indus­tri­al requirements.

We have devel­oped unique growth recipes using which we can grow car­bon nanos­truc­tures at exact posi­tions with exact required prop­er­ties. This is our core tech­nol­o­gy, and it goes by the name Smol­GROW™. Part­ners can license our tech­nol­o­gy to accom­plish solu­tions tai­lored to their unique needs and requirements.

How are CNFs manufactured?

Smolek’s fab­ri­ca­tion of car­bon nanofibers is done with Plas­ma Enhand­ed Chem­i­cal Vapor Depo­si­tion (PECVD). In this process we apply ener­gy to a car­bon-based gas, in the form of heat­ing or light­ning dis­charges, releas­ing car­bon ions that can deposit on sur­faces pre­pared with cat­alyt­ic metal.

In our Smol­GROW™ process we can exact­ly con­trol where the released car­bon atoms set­tle and how they are formed into car­bon nanofibers (or nanos­truc­tures). This gives us a unique oppor­tu­ni­ty to tai­lor car­bon nanofibers with desired prop­er­ties. We have also devel­oped the tech­nol­o­gy to use com­par­a­tive­ly low tem­per­a­tures (375 °C), which allows our man­u­fac­tur­ing tech­nique to be used in pro­duc­tion lines in the semi­con­duc­tor industry.

The Smol­GROW™ CNF man­u­fac­tur­ing process (overview):

1. The sub­strate on which the car­bon nanofibers will grow, e.g., sil­i­con wafer, is pre­pared by deposit­ing var­i­ous mate­ri­als that form an under­lay­er on which the car­bon nanofibers will grow.
2. A cat­a­lyst is deposit­ed as dots or pads where car­bon nanofibers will grow on top of the under­lay­er. These facil­i­tate a con­trolled growth of indi­vid­ual nanos­truc­tures in pre­cise locations.
3. The sub­strate is put into the PECVD-tool, which is her­met­i­cal­ly sealed and emp­tied of air, mak­ing a vac­u­um inside.

4. A car­bon-based gas is intro­duced into the reac­tor cham­ber along with oth­er gas­es that facil­i­tate the reac­tion. Typ­i­cal­ly, acety­lene is used to grow the fibers and the ammo­nia to clear excess deposition.
5. Inside the cham­ber, a huge dif­fer­ence in elec­tri­cal volt­age cre­ates an arc of light (elec­tri­cal dis­charge). This heats the gas so that elec­trons are sep­a­rat­ed from the nuclei and can move freely. The result is a soup, called plas­ma, of elec­trons and ions. The dis­charges are repeat­ed sev­er­al times per sec­ond to main­tain the plas­ma. One of the cru­cial prop­er­ties of plas­ma is that the elec­trons have an ener­gy equiv­a­lent to sev­er­al thou­sand degrees Cel­sius. At the same time, the rest of the gas is rel­a­tive­ly cool.
6. The elec­trons’ ener­gy induces the depo­si­tion of car­bon on the cat­alyt­ic dots and pads, which form a car­bon nanos­truc­ture. Smoltek can cre­ate var­i­ous car­bon nanos­truc­tures by con­trol­ling the deposit, includ­ing car­bon nanofibers with desired properties.
7. When the car­bon nanofibers have reached the desired length, the process is stopped, and the remain­ing gas­es are vent­ed out of the cham­ber again. We are left with the sub­strate with the car­bon nanofibers.

Smoltek’s tech­nol­o­gy works not only with car­bon nanofibers. It is pos­si­ble to cre­ate oth­er car­bon nanos­truc­tures, like car­bon nan­otubes (CNTs), and use mate­ri­als oth­er than carbon.