A pixel for detecting incident radiation (In) over a large area with high sensitivity and low power consumption. The pixel comprises a semiconductor substrate (1), covered by a thin insulating layer (2), on top of which a dendritic or arborescent gate structure (3) is arranged. The dendritic gate (3) is electrically connected at two or more contacts (C1, C2) with voltage sources, leading to the flow of a current and a position-dependent potential distribution in the gate (3). Due to the use of arborescent structures and various materials (31, 32), the pixel can be optimized for a certain application, in particular in terms of the electric field distribution, the RC time constant, the power consumption and the spectral sensitivity. Due to its compact size, the photo sensor can be arranged in linear or two-dimensional manner for the realization of line and area sensors.