cm9b04630_si_001.pdf (2.97 MB)
Nucleation Effects in the Atomic Layer Deposition of Nickel–Aluminum Oxide Thin Films
journal contribution
posted on 2020-02-24, 18:03 authored by Jon G. Baker, Joel R. Schneider, James A. Raiford, Camila de Paula, Stacey F. BentAtomic
layer deposition (ALD) has become an important technique
to synthesize a wide variety of materials on the subnanometer length
scale. Expanding the library of ALD for ternary materials is vital
for applications in which ternary materials allow for tuning of physical,
optical, and electronic properties. In this work, we demonstrate the
first report of nickel–aluminum oxide (Ni–Al–O)
films deposited by ALD using nickelocene-ozone and trimethylaluminum-water
as reactants. While deposition of a wide range of compositions is
achieved, the observed growth per cycle (GPC) did not follow the simple
combination of GPCs measured for the binary ALD processes. Nucleation
studies performed to better understand this behavior reveal that the
deposition of aluminum oxide is greatly enhanced on a NiO surface
prepared by nickelocene and ozone. A model is developed that considers
nucleation effects to predict composition and thickness as a function
of supercycle recipe. Characterization of the deposited films shows
that Al-doping of NiO results in contraction of the NiO lattice, decreased
crystallinity, and reduced density, and that films become completely
amorphous at compositions with less than 50% Ni. In addition, Al-doped
NiO films deposited by ALD are investigated as a hole-selective transport
layer in lead-based perovskite solar cells. An Al doping of ∼4%
improves power conversion efficiency of the perovskite-based devices
over that of NiO primarily through increases in fill factor.