Graphene / a-Si:H multispectral photodetectors

We demonstrate the integration of large area graphene transparent conductive electrodes in flexible amorphous silicon multispectral (MS) photodetectors (PD). These MS diodes show a bias dependent maximum of their spectral response between the ultraviolet (UV) and visual wavelength range. This ability to shift the response maximum by external bias without the use of filter-structures and the possibility to deposit the device structure directly onto flexible polyimide substrates gives these sensors wide applicability as one-pixel color detectors. Graphene MS PDs show an extended detection range well into the UV when compared to rigid devices with aluminum doped zinc oxide electrodes. The integration of bi-layer graphene contacts boosts the maximum spectral response up to 185 mAW-1, which is an improvement of 150 % compared to sensors with just one atom thick graphene contacts.

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