  Hydrogenated amorphous silicon (a-Si:H) has remarkable radiation resistance
properties and can be deposited on a lot of different substrates. A-Si:H based
particle detectors have been built since mid 1980s as planar p-i-n or Schottky
diode structures; the thickness of these detectors ranged from 1 to 50 micron.
However MIP detection using planar structures has always been problematic due
to the poor S/N ratio related to the high leakage current at high depletion
voltage and the low charge collection efficiency. The usage of 3D detector
architecture can be beneficial for the possibility to reduce inter-electrode
distance and increase the thickness of the detector for larger charge
generation compared to planar structures. Such a detector can be used for
future hadron colliders for its radiation resistance and also for X-ray
imaging. Furthermore the possibility of a-Si:H deposition on flexible materials
(like kapton) can be exploited to build flexible and thin beam flux measurement
detectors and x-ray dosimeters.
