Low Temperature (&lt;100°C) Deposition of Aluminum Oxide Thin Films by ALD with O[sub 3] as Oxidant

Kim, Seong Keun; Lee, Suk Woo; Hwang, Cheol Seong; Min, Yo‐Sep; Won, Jeong Yeon; Jeong, Jaehack

doi:10.1149/1.2177047

Cited by 158 publications

(135 citation statements)

References 28 publications

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“…Alumina grown this way yielded a more dense coating with the FDTD model fit parameters of n c = 1.4 and t = 4 nm. Unlike sample A, sample B was not exposed to air in between the successive layers, therefore the alumina growth rate is slightly higher, 1.25Å/cycle on the top surface, or 2.5Å/cycle inside the NG, which is consistent with growth rates reported for alumina ALD at room temperate under similar conditions [74][75][76].…”

Section: Resonance Tuningsupporting

confidence: 84%

Plasmon Enhanced Photoemission

Polyakov

2012

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Next generation ultrabright light sources will operate at megahertz repetition rates with temporal resolution in the attosecond regime. For an X-Ray Free Electron Laser (FEL) to operate at such repetition rate requires a high quantum e ciency (QE) cathode to produce electron bunches of 300 pC per 1.5 µJ incident laser pulse. Semiconductor photocathodes have su cient QE in the ultraviolet (UV) and the visible spectrum, however, they produce picosecond electron pulses due to the electron-phonon scattering. On the other hand, metals have two orders of magnitude less QE, but can produce femtosecond pulses, that are required to form the optimum electron distribution for high e ciency FEL operation. In this work, a novel metallic photocathode design is presented, where a set of nano-cavities is introduced on the metal surface to increase its QE to meet the FEL requirements, while maintaining the fast time response.Photoemission can be broken up into three steps: (1) photon absorption, (2) electron transport to the surface, and (3) crossing the metal-vacuum barrier. The first two steps can be improved by making the metal completely absorbing and by localizing the fields closer to the metal surface, thereby reducing the electron travel distance. Both of these e↵ects can be achieved by coupling the incident light to an electron density wave on the metal surface, represented by a quasi-particle, the Surface Plasmon Polariton (SPP).The photoemission then becomes a process where the photon energy is transferred to an SPP and then to an electron. The dispersion relation for the SPP defines the region of energies where such process can occur. For example, for gold, the maximum SPP energy is 2.4 eV, however, the work function is 5.6 eV, therefore, only a fourth order photoemission process is possible. In such process, four photons excite four plasmons that together excite only one electron. The yield of such non-linear process depends strongly on the light intensity.In this work, the structure consisted of rectangular nano-grooves (NGs) arranged in a subwavelength grating on a metal surface is presented that provides a dramatic increase in the metal's absorption, field localization, and field enhancement. When light is polarized perpendicular to the orientation of the grooves a standing SPP wave is excited along the vertical walls in the NGs, that act as Fabry-Perot resonators. By adjusting the geometry of 2 the NGs and the period of the subwavelength grating the resonance can be fine tuned to a desired position, for example, the laser fundamental wavelength, anywhere from the UV to the near infrared (NIR).Two types of gratings are presented: (a) a gold grating with period of 600 nm, and (b) an aluminum-gold grating with a period of 100 nm; both with resonance at 720 nm. In each case, strong on-resonance absorption was observed, with over 98% for grating (b). Unlike the grating-coupled SPP waves, where the angle is well defined by the momentum matching condition, the resonant NGs allow coupling to the standing modes at a range...

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Section: Resonance Tuningsupporting

confidence: 84%

Plasmon Enhanced Photoemission

Polyakov

2012

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“…For instance, ozone (O 3 ) can be used as an oxidant. 9 However, this is slightly more complex as it requires an ozone generator with a sufficiently high O 3 production rate. Particularly when going to high throughput applications where large amounts of ozone are required, this might become too costly.…”

Section: B Alternatives For Watermentioning

confidence: 99%

Low temperature and roll-to-roll spatial atomic layer deposition for flexible electronics

Poodt¹,

Knaapen²,

Illiberi³

et al. 2011

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Spatial atomic layer deposition can be used as a high-throughput manufacturing technique in functional thin film deposition for applications such as flexible electronics. This; however, requires low-temperature processing and handling of flexible substrates. The authors investigate the process conditions under which low-temperature spatial atomic layer deposition of alumina from trimethyl aluminum and water is possible. The water partial pressure is the critical parameter in this case. Finally, our approach to roll-to-roll spatial atomic layer deposition is discussed.

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“…Carbon atoms are common impurities affecting the passivation quality of Al2O3 layers [5,7,8], and are considered harmful for surface passivation. Although ozone possesses a stronger oxidation potential than water, and has potentially beneficial effect on the reduction of impurity concentrations, as shown in previous studies [5,[8][9][10], other studies have also reported relatively high carbon concentration in ozone-based ALD films [11,12]. Despite this possible drawback, ozone-based ALD Al2O3 shows promising surface passivation quality [6,13].…”

Section: Introductionmentioning

confidence: 96%