The advent of “flexible” electronics on plastic substrates with low melting points requires the development of thin film
deposition techniques that operate at low temperatures. This is easily achieved with vacuum or solution
-
processed
molecular or
polymeric semiconductors, but oxide materials remain a significant challenge. Here we show that zinc oxide (ZnO) can be prep
ared
using only room
-
temperature processes, using
the
molecular thin film precursor zinc phthalocyanine (ZnPc), follow
ed by vacuum
ultra
-
violet light treatment to elicit degradation of the organic components and transformation of the deposited film to oxide mate
rial.
The degradation mechanism was assessed by studying the influence of the atmosphere during the reaction: i
t was particularly sensitive
to oxygen pressure in the chamber and optimal degradation conditions were established as 3 mbar with 40% oxygen in nitrogen.
The
morphology of the film was relatively unchanged during the reaction, but detailed analysis of its
composition using both scanning
transmission electron microscopy (STEM) and secondary ion mass spectrometry (SIMS) revealed that a 40 nm thick layer
containing
ZnO results from the 100 nm thick precursor after complete reaction. Our methodology represent
s a simple route for the fabrication
of oxides and multilayer structures
that can be
easily
integrated into current molecular thin film growth setups,
without the n
eed for
a high temperature step
.