Giant photosensitivity of a-C:Co/GaAs/Ag p-n-metal junctions

The Schottky contact behavior of Silver (Ag) with parts of semiconductor materials, such as GaAs and GaN, greatly limits its application for electrodes in electronic devices. Here, a giant photosensitivity is observed in Co-doped amorphous carbon (a-C:Co) films deposited on n-type low-resistance GaAs substrates through a Schottky contact between GaAs and Ag. We ascribe the giant photosensitivity to the turn-on voltage difference in the series-opposing connected a-C:Co/GaAs photosensitive diode and GaAs/Ag Schottky junction with and without light illumination, and also to the surface plasmon resonance absorption of Co nanoparticles.