A comparison of Monte Carlo and analytic treatments of displacement damage in Si microvolumes

Solid state sensor arrays are increasingly being used in space for numerous applications including multispectral imaging, intersatellite communications, spectroscopy, and star tracking. Particle-induced degradation of charge coupled devices (CCDs) and charge injection devices (CIDs) can be dominated by displacement damage which increases the pixel dark current and degrades the charge transfer efficiency (CTE). In this paper, the authors compare Monte Carlo and analytic calculations of displacement damage resulting from inelastic proton reactions in Si. These comparison include the nonionizing energy loss rate, the mean recoil damage energy spectra, and their associated variance. In the limit of bulk material, both approaches are in good agreement. As sensitive volumes shrink and incident proton energies increase, the ranges of the spallation recoil fragments approach the smallest dimension of the microvolume, and the pixel-to-pixel damage variance increases rapidly. In this regime, a Monte Carlo approach is used to describe the damage energy distribution. Indeed, they show that such simulations predict the 63 MeV proton-induced dark current histograms more accurately than present analytic methods. The Monte Carlo code is also used to explore ground test fidelity issues for devices with small sensitive volumes