  The eventual exploitation of one-dimensional nanomaterials yet needs the
development of scalable, high yield, homogeneous, and environmentally friendly
methods able to meet the requirements for the fabrication of under design
functional nanomaterials. In this article, we demonstrate a vacuum and plasma
one-reactor approach for the synthesis of the fundamental common element in
solar energy and optoelectronics, i.e. the transparent conducting electrode but
in the form of nanotubes and nanotrees architectures. Although the process is
generic and can be used for a variety of TCOs and wide-bandgap semiconductors,
we focus herein on Indium Doped Tin Oxide (ITO) as the most extended in the
previous applications. This protocol combines widely applied deposition
techniques such as thermal evaporation for the formation of organic nanowires
serving as 1D and 3D soft templates, deposition of polycrystalline layers by
magnetron sputtering, and removal of the template by simply annealing under
mild vacuum conditions. The process variables are tuned to control the
stoichiometry, morphology, and alignment of the ITO nanotubes and nanotrees.
Four-probe characterization reveals the improved lateral connectivity of the
ITO nanotrees and applied on individual nanotubes shows resistivities as low as
3.5 +/- 0.9 x 10-4 {\Omega}.cm, a value comparable to single-crystalline
counterparts. The assessment of diffuse reflectance and transmittance in the
UV-VIS range confirms the viability of the supported ITO nanotubes as a random
optical media working as strong scattering layers. Further ability to form ITO
nanotrees opens the path for practical applications as ultra-broadband
absorbers in the NIR. The demonstrated low resistivity and optical properties
of these ITO nanostructures open the way for their use in LEDs, IR shield,
energy harvesting, nanosensors, and photoelectrochemical applications
