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Volumn 6, Issue 10, 2010, Pages 1117-1124

Mimicking electrodeposition in the gas phase: A programmable concept for selected-area fabrication of multimaterial nanostructures

Author keywords

Clusters; Electrodeposition; Interconnects; Nanostructures; Sensors

Indexed keywords

CHARGED CLUSTERS; CLUSTERS; GAS PHASE PROCESS; GASPHASE; IN-SITU; INTERCONNECTS; LIQUID PHASE; MIX AND MATCH; MULTI MATERIALS; NANOPARTICLE FILMS; PRESSURE RANGES; PUMPLESS; ROOM TEMPERATURE; SUBSTRATE REGIONS; TIO; ZNO;

EID: 77952677612     PISSN: 16136810     EISSN: 16136829     Source Type: Journal    
DOI: 10.1002/smll.200901547     Document Type: Article
Times cited : (15)

References (32)
  • 13
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    • (1991) Nature , vol.354 , pp. 56
    • Iijima, S.1
  • 21
    • 77952692768 scopus 로고    scopus 로고
    • note
    • Characteristic spectral emission from pure Ar discharges includes red-purple emission peaks at 697nm due to ionization of Ar molecules into Arp and at 481nm for Arpp, while blue-white O2 discharges contain ionized peaks at 419nm due to O2+ ++ and at 646 and 777nm due to the dissociation of the O2 molecule into atomic O. The noble gases that we used to provide the inert environment discussed later (Ar, He) show similar basic arc characteristics and are also known to release electrons by charging to a positively ionized state.
  • 23
    • 77952723584 scopus 로고    scopus 로고
    • note
    • High-current 100 A arc discharges, classically referred to as hightemperature thermal plasmas or plasma sprays, describe a case where the electrons and ions are in thermal equilibrium and sufficiently hot to quickly evaporate the cathode material. However, erosion and the production of nanoparticles has been reported even under corona discharge conditions, which sustain much smaller currents, typically less than 500μA. The input power used in the experiments reported here ranged between 1 and 100W with controlled arc currents of less than 100mA, which is quite similar to what is used in atmospheric-pressure arc discharge lamps. We anticipate that higher current levels are most likely going to work as well.
  • 24
    • 77952693130 scopus 로고    scopus 로고
    • note
    • The consideration that nanoparticles originate from the grounded cathode and do not deposit on insulating surfaces leads to the conclusions that Coulomb forces dominate the deposition process and that nanoparticles charge to be unipolar prior to deposition on the sample electrode. If neutral particles were present they would coat the insulating surfaces and this is not the case. If the aerosol were to have both positively and negatively charged particles above the sample surface, we would again anticipate that the insulating surface would build up a particle layer, contrary to observation. The material flux forming the deposits (Figure 3F,G), together with the recorded positive-ion current and absence of deposition on the insulating surfaces, can only be explained if the nanomaterials are predominantly positively charged. Insulating surfaces are initially uncharged and we would expect a limited amount of charged material to deposit until the insulator fully charges. Such deposition is not observed within the ≈5nm resolution limit of our SEM instrument. This behavior can be explained if we consider the higher mobility of gas ions when compared to nanoparticles. Gas ions such as Arp in Figure 3 are likely to be responsible for establishing an equilibrium charge and potential distribution as the experiment is started. As indicated in Figure 3C, Arp ions surrounding the insulator are expected to be responsible for preventing deposition of the positively charged M+ nanoparticles on the insulator.
  • 25
    • 77952704449 scopus 로고    scopus 로고
    • note
    • Sheath regions (purple near cathode and green near anode in Figure 5A) are confined to distances on the order of the Debye length of the high-mobility electrons in the system. The anode sheath accumulates a negative space charge dominated by highmobility electrons, whereas the cathode sheath is depleted of free electrons yielding a positive space-charge region of primarily Ar+ ions when considering the depicted argon plasma situation. We refer to Lichtenberg et al.[27] for detailed calculations of the sheath region at the cathode of an arc discharge lamp. The Debye length is rD=√[(k×ε0/e2)(Te/ne)], where k is the Boltzmann constant (8.62-10-5 eV K-1) and ε0 is the permittivity of free space (8.854-10-12Fm-1), and this electrostatic shielding length depends on the ratio between the electron temperature Te and electron concentration ne. The range of possible values is great: ne=1016 cm-3, Te=22000 K, and rD=200nm are common for a high 6 A atmospheric-pressure arc, whereas ne=108 cm-3, Te=11600 K, and rD=0.7mm have been discussed for a lowercurrent corona discharge.
  • 31
    • 77952719926 scopus 로고    scopus 로고
    • note
    • The competition between neighboring areas attracting materials within the Debye radius could in principle affect the deposition rate. However, we have not been able to increase the deposition rate on going from a dense pattern to an isolated line, which suggests that diffusion plays a role in the observed uniformity.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.