Measurement and Simulation of the Variation in Proton-Induced Energy Deposition in Large Silicon Diode Arrays Christina L. Howe 1, Robert A. Weller 1, Robert A. Reed 1, Brian D. Sierawski 2, Paul W. Marshall 3, Cheryl J. Marshall 4, Marcus H. Mendenhall 5, Ronald D. Schrimpf 1, and J. E. Hubbs 6 1. Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN Institute for Space and Defense Electronics, Vanderbilt University, Nashville, TN Consultant, Brookneal, VA NASA-GSFC, Greenbelt, MD Free-Electron Laser Center, Vanderbilt University, Nashville, TN Ball Aerospace & Technologies Corp., Albuquerque, NM 87117

Outline Background Motivation Experimental Setup Modeling Description Results –Simulation compared with experimental results –Contribution from reaction mechanisms –Event rate calculation Conclusions Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Background Focal plane arrays (FPAs) often used on satellites planned for long orbits in harsh proton environments FPAs Advantages –Flexible, reliable, low cost, high-density resolution, on- chip signal processing, and more radiation tolerant to protons than charge coupled devices (CCDs) Detector Array In ROIC Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays Basic hybrid FPA

Motivation Proton events contribute to device noise floor Better understanding of how radiation-induced energy deposition occurs will improve prediction techniques Accurate modeling helps predict on-orbit response We will show a high-fidelity prediction method based on Monte Carlo simulations and a mathematical model Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Experimental Setup Hybrid FPA consisting of a silicon p-i-n 128 × 128 detector array with hardened CMOS readout integrated circuit (ROIC) Full radiometric characterizations were performed –Dark current, noise, responsivity, and sensitivity Irradiated with 63 MeV protons at 45° Biased to 15V resulting in full depletion Exposed at 233 K Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Modeling Description MRED (Monte Carlo Radiative Energy Deposition), a GEANT4 based tool, used for simulation Sensitive Volume 45° 63 MeV Proton Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays TCAD simulations revealed RPP assumption was sufficient to estimate device response to radiation

Modeling Description Each event in Monte Carlo simulation represents only one primary particle hit one pixel, but… –Non-negligible probability of multiple hits on a single pixel (pile up) exists –Non radiation induced noise in experimental data Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Pile Up Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays µ = 0.08 σ NOISE = 3 Before Pile Up After Pile Up

Results Statistical floor of experimental data Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Constant-LET and Path Length Distribution Calculation Does not predict occurrence of large energy depositions Does not predict shape of curve Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Reaction Mechanisms Nuclear reactions dominate above 500 keV Coulomb scattering does not contribute significantly here Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Event Rate Simulations Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays Proton environments from CREME GEO – peak five minutes and worst week ISS – space station orbit, apmin8

GEO Event Rate Simulations Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

ISS Event Rate Simulations Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays

Conclusions The on-orbit response can be predicted with greater detail than available through experiment at energies greater than 700 keV Energy events greater than 130 keV are not predicted by path length calculation for this device Nuclear reactions dominate the event rate at energies greater than 3 MeV Measurement and Simulation of the Variation in Proton- Induced Energy Deposition in Large Silicon Diode Arrays