01036nas a2200169 4500008003900000022001400039245008800053210006900141260001200210300001600222490000700238520048400245100001900729700001700748700002200765856007900787 2014 d a0093-381300aDrifting Ionization Zone in DC Magnetron Sputtering Discharges at Very Low Currents0 aDrifting Ionization Zone in DC Magnetron Sputtering Discharges a c10/2014 a2578 - 25790 v423 a

Discharges with crossed electric and magnetic fields are known to develop instabilities that are crucial in the transport of charged particles. Sputtering magnetrons are no exception. While most recent studies focused on traveling ionization zones in high power impulse magnetron sputtering, we show here fast camera images of magnetron discharges at very low current. A single drifting ionization zone is always present, even down to the threshold current of about 10 mA.

1 aAnders, André1 aNi, Pavel, A1 aAndersson, Joakim uhttps://facades.lbl.gov/publications/drifting-ionization-zone-dc-magnetron01455nas a2200253 4500008003900000022001300039245012000052210006900172260001200241300001100253490000800264520065900272653002000931653001500951653002200966653002300988653001501011100001901026700002101045700001801066700002201084700001801106856007701124 2013 d a0003695100aDrifting potential humps in ionization zones: The “propeller blades” of high power impulse magnetron sputtering0 aDrifting potential humps in ionization zones The propeller blade c10/2013 a1441030 v1033 a

Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E × B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

10aElectric fields10aionization10aplasma ionization10asputter deposition10asputtering1 aAnders, André1 aPanjan, Matjaž1 aFranz, Robert1 aAndersson, Joakim1 aNi, Pavel, A. uhttps://facades.lbl.gov/publications/drifting-potential-humps-ionization01380nas a2200229 4500008003900000022001300039245009800052210006900150260001200219300001100231490000800242520068000250653001400930653001500944653002300959653002200982653002001004100002201024700001701046700001901063856006801082 2013 d a0003695100aSpectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas0 aSpectroscopic imaging of selforganization in high power impulse  c07/2013 a0541040 v1033 a

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

10aAluminium10aionization10aIonizing radiation10aplasma ionization10avisible spectra1 aAndersson, Joakim1 aNi, Pavel, A1 aAnders, André uhttps://facades.lbl.gov/publications/spectroscopic-imaging-self01581nas a2200181 4500008004100000050001500041245011400056210006900170520095200239100001901191700002201210700001701232700002201249700002001271700002001291700001601311856007201327 2009 eng d aLBNL-1881E00aHigh quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition0 aHigh quality ZnOAl transparent conducting oxide films synthesize3 a

Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200°C, have resistivities in the low to mid 10-4Ω cm range with a transmittance better than 85% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.

1 aAnders, André1 aLim, Sunnie, H.N.1 aYu, Kin, Man1 aAndersson, Joakim1 aRosén, Johanna1 aMcFarland, Mike1 aBrown, Jeff uhttps://facades.lbl.gov/publications/high-quality-znoal-transparent01116nas a2200145 4500008004100000050001400041245010200055210006900157300001100226490000700237520061100244100002200855700001900877856007400896 2008 eng d aLBNL-190E00aGasless sputtering: Opportunities for ultraclean metallization, coatings in space, and propulsion0 aGasless sputtering Opportunities for ultraclean metallization co a2215030 v923 a

Pulsed magnetron sputtering was demonstrated in high vacuum: no sputter gas was used at any time. Sustained selfsputtering was initiated by multiply charged ions from a short vacuum arc. Copper ion currents to an ion collector in excess of 30 A were measured, implying a plasma density of about 6 x1018 m-3. This technology may prove useful for metal coatings free of noble gas inclusions and suggests that magnetrons could operate in the vacuum of space. In addition to coating objects in space, the momentum of the sputtered atoms and ions may be utilized in space thrusters.

1 aAndersson, Joakim1 aAnders, André uhttps://facades.lbl.gov/publications/gasless-sputtering-opportunities01008nas a2200157 4500008004100000245008100041210006900122260001200191300001000203490000700213520048800220100002200708700002800730700001900758856007300777 2008 eng d00aObservation of Ti4+ ions in a high power impulse magnetron sputtering plasma0 aObservation of Ti4 ions in a high power impulse magnetron sputte c08/2008 a715040 v933 a

Multiply charged titanium ions including Ti4+ were observed in high power impulse magnetron sputtering discharges. Mass/charge spectrometry was used to identify metal ion species. Quadruply charged titanium ions were identified by isotope-induced broadening at mass/charge 12. Due to their high potential energy, Ti4+ ions give a high yield of secondary electrons, which in turn are likely to be responsible for the generation of multiply charged states.

1 aAndersson, Joakim1 aEhiasarian, Arutiun, P.1 aAnders, André uhttps://facades.lbl.gov/publications/observation-ti4-ions-high-power01049nas a2200121 4500008004100000050001500041245009000056210006900146520059600215100002200811700001900833856007500852 2008 eng d aLBNL-1641E00aSelf-sputtering far above the runaway threshold: an extraordinary metal ion generator0 aSelfsputtering far above the runaway threshold an extraordinary 3 a

When self-sputtering is driven far above the runaway threshold voltage, energetic electrons are made available to produce excess plasma far from the magnetron target. Ionization balance considerations show that the secondary electrons deliver the necessary energy to the remote zone. Thereby, such a system can be an extraordinarily prolific generator of useable metal ions. Contrary to other known sources, the ion current to a substrate can exceed the discharge current. For gasless self-sputtering of copper, the useable ion current scales exponentially with the discharge voltage.

1 aAndersson, Joakim1 aAnders, André uhttps://facades.lbl.gov/publications/self-sputtering-far-above-runaway01855nas a2200145 4500008004100000050001500041245005500056210005500111520137800166100001901544700002201563700001801585700002801603856007801631 2007 eng d aLBNL-6214700aPhysics of High Power Impulse Magnetron Sputtering0 aPhysics of High Power Impulse Magnetron Sputtering3 a

High power impulse magnetron sputtering is characterized by discharge pulses whose target power density exceeds conventional sputtering power densities by two orders of magnitude or more; the goal is to provide a large flux of ionized sputtered material. The processes of pulse evolution are briefly reviewed, including secondary electron emission, self-sputtering, and rarefaction. Using a pulse power supply capable of providing constant voltage for target peak power densities up to 5 kW/cm2, the evolution of the current-voltage characteristics was investigated for copper and titanium. It is shown that the characteristic cannot be reduced to value pairs. Rather, a strong but reproducible development exists. The details depend on the argon pressure and applied voltage. Each target material exhibits a distinct and sharp transition to a high current regime that appears to be dominated by metal plasma. Despite the higher sputter yields for copper, the transition to the high current regime occurs much earlier and stronger for titanium, which may be attributed to a higher secondary electron yield and hence a higher density of electrons confined in the magnetron structure. At high currents, the closed-drift Hall current generates a magnetic field that weakens plasma confinement, thereby enabling large ion currents to reach a biased substrate.

1 aAnders, André1 aAndersson, Joakim1 aHorwat, David1 aEhiasarian, Arutiun, P. uhttps://facades.lbl.gov/publications/physics-high-power-impulse-magnetron