Nanocomposite coatings by ALD: in-situ growth investigation and applications (Conference Presentation)

We have established ALD methodology to synthesize nanocomposite coatings comprised of conducting, metallic nanoparticles embedded in an amorphous dielectric matrix. These films are nominally composed of M:Al2O3 where (M= W, Mo, and Ta) and are prepared using alternating exposures to trimethyl aluminum (TMA) and H2O for the Al2O3 ALD and alternating MF6/Si2H6 exposures for the metal ALD. By varying the ratio of ALD cycles for the metal and the Al2O3 components during material growth, we can tune precisely the various material properties such as microstructure, electrical, optical and chemical properties. The resistance of these coatings can be controlled over a very broad range (e.g. 1e11-1e4 Ohm-cm) and these films exhibit Ohmic behavior and resist breakdown even at high electric fields of <1e7 V/m. Moreover, the self-limiting nature of ALD allows us to grow these films inside of high aspect ratio substrates and on complex 3D surfaces. We have exploited these nanocomposite coatings for applications such as functionalization of large-area microchannel plates suitable for area photodetectors, charge drain coatings for electron optic MEMS devices (Digital Pattern Generation chips) for maskless reflection electron beam lithography system, protective coatings for Li-ion battery cathodes and solar selective absorber coating for high temperature concentrated solar power (CSP). Here we will discuss the ALD in-situ growth study, various nanocomposite material characterizations, and some of these applications.