Abstract: Disclosed herein is a system for detecting cancer cells. The system includes a biosensor comprising a graphene-Si Schottky junction, a light source placed above the biosensor, an electrical stimulator-analyzer connected to the biosensor, and a processing unit connected to the electrical stimulator-analyzer and the light source. The processing unit is configured to perform a method. The method includes generating a set of photocurrents in a reverse bias regime passed through the graphene-Si Schottky junction with a sample placed thereon utilizing the light source and the electrical stimulator-analyzer, measuring the set of the generated photocurrents through the graphene-semiconductor Schottky junction in reverse bias regime in the presence of the sample utilizing the electrical stimulator-analyzer device, and detecting a presence of cancer cells in the sample responsive to detecting a change in the measured set of the generated photocurrents within the reverse bias regime.