Determination of the spatial variation of the carrier lifetime in a proton-irradiated Si n+-n-p+ diode by optical-beam-induced current measurements

It is shown that the local carrier diffusion length can be obtained from optical-beam-induced current (OBIC) measurements on a diode structure with the p-n junction perpendicular to the surface by evaluating the local slope of the OBIC signal, when the light penetration depth is sufficient and when the sample can be considered semi-infinite. The method is applied to several n⁺-n-p⁺ diodes which were proton-irradiated at various proton fluxes. The measured lifetime profiles after proton irradiation are found to agree very well with defect profiles