Steady-State Response of Silicon Radiation Detectors of the Diffused p-n Junction Type to X Rays. I: Photovoltaic Mode of Operation

Abstract

A relation is derived for the photocurrent produced by x rays in silicon radiation detector cells of the p-n junction type, giving the dependence of the generated photocurrent on exposure rate, photon energy, and electrical and geometrical parameters of the silicon wafer. Silicon radiation detector cells operated as photovoltaic cells are found to be more sensitive to x rays than silicon solar cells previously investigated, open-circuit voltages being several hundred times larger than those measured in solar cells. The short-circuit current produced by x rays increases with increasing temperature by about 0.3 percent per °C at 25 °C cell temperature. Due to the high zero voltage junction resistance of silicon radiation detector cells, the temperature dependence of the photovoltaic output current increases with increasing load resistance at a smaller rate than that observed in silicon solar cells. The energy dependence of the short-circuit current produced by x rays, measured over a wide range of radiation qualities, is shown to be in good qualitative agreement with calculated values.