  Graphene is of increasing interest for optoelectronic applications exploiting
light detection, light emission and light modulation. Intrinsically light
matter interaction in graphene is of a broadband type. However by integrating
graphene into optical micro cavities also narrow band light emitters and
detectors have been demonstrated. The devices benefit from the transparency,
conductivity and processability of the atomically thin material. To this end we
explore in this work the feasibility of replacing graphene by nanocrystalline
graphene, a material which can be grown on dielectric surfaces without catalyst
by graphitization of polymeric films. We have studied the formation of
nanocrystalline graphene on various substrates and under different
graphitization conditions. The samples were characterized by resistance,
optical transmission, Raman, X-ray photoelectron spectroscopy, atomic force
microscopy and electron microscopy measurements. The conducting and transparent
wafer-scale material with nanometer grain size was also patterned and
integrated into devices for studying light-matter interaction. The measurements
show that nanocrystalline graphene can be exploited as an incandescent emitter
and bolometric detector similar to crystalline graphene. Moreover the material
exhibits piezoresistive behavior which makes nanocrystalline graphene
interesting for transparent strain sensors.
