A method of forming a semiconductor detector including: forming a p-n junction diode in an active device layer of a silicon-on-insulator (SOI) substrate, the active device layer being formed on an insulator layer of the SOI substrate; forming a first opening through the insulator layer to access a backside of a first doped region of the diode, the first doped region underlying a second doped region of the diode; forming a back contact on a back surface of the first doped region and electrically connecting with the first doped region; forming a conductive interconnect layer on an upper surface of the SOI substrate, the interconnect layer including a first top contact providing electrical connection with the second doped region; and forming an electrode in the first opening on the backside of the detector structure, the electrode providing electrical connection with the back contact of the diode.