Steady-state response of silicon radiation detectors of the diffused p-n junction type to x rays. II. Photodiode mode of operation

Abstract

A relation is d erived for the photo cUl'rent produced by x rays in silicon radiation detector cells of the P7n junction type, giving the d ependence of the generated photo current on cxposure rate, photon e nergy, a nd clectri cal and geometrical parameters of the silicon wafer. Si li co n r a diation detcctor cells operated as photovoltaic cells are found to be more se nsit ive to x rays than sili co n solar cells prcviously investigated, opcn-circuit voltages being sevcral hundred times larger t han t hose measured in solar cells . The s hort-circui t current produced by x rays in creases with in creasing temperature by about 0.3 pOl'ce nt per °0 at 25 °0 cell te mperature. Due to the high zero voltage jun ction resis tance o f sili con rad iation detector cells, t he temperatUJ'e dependence of the photovo ltaic output current in creases wi t h increasin g load resis tance at a s ma ll er rate than that observed in silicon solar cells. The energy d epende nce of the s hort-circuit current produced by x rays, measlll'ed over a wide range of radiatio n qualities, is s llOwn to be in good qualitative agreement with calculated values.