tronic device types such as the charge injection device (CID) and charge coupled device (CCD), which are extremely sensitive to displacement damage. CCDs are subject to dark current increases resulting from decreased generation lifetime, and from charge transfer efficiency (CTE) degradation due to carrier trapping. JFET and MESFET technologies, being majority carrier devices, are generally very robust to displacement damage [e.g., Hash94] although their transconductance may be degraded by carrier removal at high proton exposure levels. Table 1 summarizes the relative importance (primary or secondary) of displacement damage in many common device technologies [after Srou88a]. Radiation effects experience over the last 20 years has led to a general understanding of device type sensitivities and degradation modes in response to displacement damage. Summaries of these efforts may be found in general radiation effects texts [e.g., Mess86, Holm93] and in a number of summary papers [e.g., Gove84, Srou88b, Raym87]. The case studies to be considered in this course will also provide brief descriptions of displacement damage effects in selected device types. IV-58 Table 1. Displacement Damage Mechanisms for Various Technologies ¹ Component Lifetime Carrier Trapping Mobility Degradation Removal Degradation Si MOS Transistors & ICs Charged Coupled Devices Si Bipolar Transistors & Linear ICs Photodetectors LEDs & Laser Diodes pn Junctions JFETs GaAs Transistors & ICs P = Primary; S = Secondary After [Srou88a]. Note that TID and SEEs also can be primary radiation concerns for these technologies. 2.3 Non-Ionizing Energy Loss Rate (NIEL) Concept As we will see in the next section, it has been shown that the radiation response of many devices can be predicted reasonably well based on calculations of the amount of displacement damage energy imparted to the primary knock-on atoms. The non-ionizing energy loss rate (NIEL) can be calculated analytically from first principles based on differential cross sections and interaction kinemati