e, the generation lifetime [Schr82], the majority carrier concentration and the majority carrier mobility. Typically, the semiconductor material quality is high SO that there is at least an order of magnitude smaller density of recombination and generation centers as compared to the majority carrier concentration. As a result, the proton induced introduction of defects (i.e., recombination centers) will impact the minority carrier lifetime well before there is a noticeable reduction in carrier concentration. The same is true for defects produced in depletion regions that can act to decrease the generation lifetime. Mobility degradation is not generally an issue except at very high displacement damage levels. Hence, devices whose primary characteristics depend on minority carrier or generation lifetimes will be most sensitive to displacement damage. Radiation induced degradation in the carrier lifetime, carrier concentration and mobility in turn impact device characteristics such as transistor gain, transconductance and saturation voltage, dark current, detector responsivity, etc. As just described, the reduction of the minority carrier lifetime is a principal cause of degradation in a number of device types. Examples include gain reduction in bipolar transistors and silicon controlled rectifiers (SCRs), reduced responsivity in photodiodes and Schottky-barrier diodes, decreased solar cell efficiency, etc. Devices with lightly doped active regions are most susceptible to degradation caused by carrier removal. Semiconductor light sources such as lasers and LEDs are generally relatively radiation hard since the carrier lifetimes in the active device regions are very short. However, amphoterically-doped LEDs, employed in some optocouplers, are a notable exception and are quite sensitive to proton induced displacement damage for reasons that are not completely understood. Displacement damage effects do not limit the performance of most MOS devices, which depend on majority carrier transport. Exceptions include optoelec