Abstract: We have developed an atomic layer deposition (ALD) method to synthesize nanocomposite coatings composed 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 by 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 in the film, we can precisely tune the resistance of these coatings over a very broad range (1011-104 ohm-cm). These films exhibit ohmic behavior and resist breakdown even at high electric fields of 107 V/m. Moreover, the self-limiting nature of ALD allows us to grow these films inside of high aspect ratio substrates and on complex 3-D surfaces.
We have used these nanocomposite coatings for various applications, such as fabrication of large-area MCPs for photodetectors, charge drain coatings in MEMS devices for a maskless reflection electron-beam lithography tool, corrosion protection coatings for lithium-ion batteries, and solar absorber coating for concentrated solar power applications. Here we will discuss in situ growth, characterization, and applications of ALD nanocomposite coatings.