Graphene-Enabled Silicon-Integrated Photodiode for DUV Imaging

We present a novel scalable graphene-silicon hybrid photodiode that enables deep UV imaging. We have a created a photodiode with a reduced dead layer entrance window. Existing photodiodes are limited in sensitivity for low wavelengths due to the low penetration depth of photons of < 400 nm. Typical photodiodes have a junction implant which causes the low penetrating photons to be recombined in this dead layer. Here, we have utilized the near transparent nature of single layer graphene to create a junction with a minimum dead layer. To have a full active bulk volume we have combined a single junction ring (n++ bias ring) with single layer graphene. The graphene acts as a large field plate which overhangs the junction ring, on top of a thin dielectric, and covers the entire active area, 5×5 mm
²
. Transient Current Technique measurements have been performed to study the charge uniformity of the device and it has been shown that the charge collected is 100% across the entire area of the detector. Additional characterisations have been performed to evaluate the sensitivity of the device as a function of wavelength in comparison to a device with an ultra-shallow junction implant. The results show that the graphene-enhanced device shows far greater performance in the 200–400 nm wavelength range.