Optimization of PIN Photodiodes Parameters for Enhanced Proton Radiation Tolerance Based on Numerical Simulations

M.A.CAPPELLETTI; A.P.CEDOLA; E.L.PELTZER Y BLANCA

University of Maryland, USA

Workshop; ISDRS 2007 International Semiconductor Device Research Symposium; 2007

IEEE - University of Maryland

Title <!-- @page { size: 8.5in 11in; margin: 0.79in } P { margin-bottom: 0.08in } --> Present work is focused on study of radiation induced displacement damage effects [1, 2] on silicon PIN photodiodes at both, dark and illumination conditions, by mean of numerical simulations. In particular, 10 MeV protons at a maximum fluence of 2.5  1014 p+/cm2 were considered. Structures with total lengths (LT) of 50 μm were simulated, with different intrinsic layer lengths (LI from 50% to 90% of LT), identical applied bias (-10V) and doping profiles. Dark current and total reverse current (sum of dark + photogeneration components) variations with proton fluence have been analyzed for these devices. At a given incident light intensity (named LIT, Light Intensity Threshold [3]) and wavelength, a value of intrinsic layer length exists (named IRTT, Intrinsic Region Thickness Threshold) for which total reverse current change with radiation is negligible (Fig. 1). This is due to compensation of photocurrent (IPH) decrease with dark current (IDARK) increase as a consequence of permanent damages induced in silicon by radiation. IRTT is the point at which total current curves with and without radiation intersects. For LI values lower than IRTT total current decreases with radiation, whereas for LI values greater than IRTT total current increases.