There are three main kinds of effects of radiation environments on electronics.
1.) Effects due to ionizing radiation (TID)
2.) Effects due to (usually heavy) charged particles (SEE)
3.) Effects due to mechanical impact (DD)
Total Ionizing Dose (TID) is considered a cumulative effect, as opposed to a single event effect. This means that one does accumulate a certain dose over time, and this accumulated dose slowly alters
parameters of your electronic device. In a Bipolar Junction Transistor, it is mainly the base current that increases with dose, while the collector current stays the same. In effect, this is a
reduction in current gain.
DD is a shorthand notation for Displacement Damage. Here, lattice atoms are physically displaced from their lattice position due to mechanical impact of a particle. This is also considered a cumulative
effect, as the damage created is - as a first order approximation - proportional to the dose of particles that impinge on the semiconductor.
Single-Event Effects or SEE in contrast are effects caused by a single particle penetrating the semiconductor. As the particle traverses the semiconductor material, it is losing kinetic energy. This energy
is not really lost however, it is transferred to the semiconductor crystal where it is used to excite electrons from the valence band to the conduction band, creating electron-hole pairs. Well, to be more
correct this energy transfer happens in all materials, not only semiconductors. Even within isolators, these electron-hole pairs are created, an depending on the type of isolator, thse charges might
actually be separated. Quite often, the electrons are swept out while the holes stay, leaving a net charge behind. SEE actually are a group of events, which are separated into a few categories based on the
impact they have on your circuit. They all start out as a bunch of charge carriers that are liberated along the particle track. Depending on the electric fields in the semiconductor, these charges might
separate. They drift and diffuse in the semiconductor as dictated by the fields. A portion of the charge - again dependent on the local electric fields - will just recombine, dissipating their energy as
heat. The stronger the electric fields, the lower the portion of electron-hole-pairs that recombine as chrges are swept out more quickly in stronger fields. In isolation oxides in a MOS devices, this
sudden availability of carriers causes electric current through the oxide, which in many cases is so high as to locally destroy the oxide, often shorting the gate to the channel. This would be termed a
Single-Event Gate Rupture (SEGR) and definitely is a catastropic event (at least for the device...). In extreme cases, this can turn a highly sophisticated piece of equipment into a very expensive
paperweight.
