Development of the silicon photo-strip sensor

We have designed and fabricated silicon photo-strip sensors with polysilicon resistors and coupling capacitors. This developed detector consists of two photo-strip sensors sandwiching opposite faces of a crystal scintillator and being oriented orthogonal to each other. This configuration is able to provides the 2 dimensional position information and to measure the energy. Therefore they can be used in nuclear and medical application. The developed sensor has p⁺ strip array for signal readout. On the other hand, the rear side is a light entrance window which has very thin n⁺ doping layer with anti-reflective coating to prevent light losing. These sensors are fabricated on a 5-in., 380 μ-thickness, n-type, high resistivity silicon wafer. The leakage currents of the fabricated sensors are measured as a function of the reverse bias voltages. The light responses of fabricated silicon photosensors coupled with a CsI(Tl) crystal are measured by using ²⁴¹Am, ²²Na and ¹³⁷Cs radioactive sources. The energy resolutions of the photodiode coupled with the crystal are obtained to be 20.5 % and 13.8 % for the ²²Na (511 keV) and the ¹³⁷Cs (662 keV) γ-rays. The one-dimensional position information by the α particles (²⁴¹Am) are clearly observed by the photo-strip sensor coupled with the crystal.