Editing Radiation hardening (section)

===Fundamental mechanisms===
Two fundamental damage mechanisms take place:

====Lattice displacement====
Lattice displacement is caused by [[neutron]]s, protons, alpha particles, heavy ions, and very high energy [[gamma photon]]s. They change the arrangement of the atoms in the [[crystal lattice]], creating lasting damage, and increasing the number of [[Carrier generation and recombination|recombination center]]s, depleting the [[minority carrier]]s and worsening the analog properties of the affected semiconductor [[p-n junction|junctions]]. Counterintuitively, higher doses over a short time cause partial [[Annealing (metallurgy)|annealing]] ("healing") of the damaged lattice, leading to a lower degree of damage than with the same doses delivered in low intensity over a long time (LDR or Low Dose Rate). This type of problem is particularly significant in [[bipolar transistor]]s, which are dependent on minority carriers in their base regions; increased losses caused by [[recombination (physics)|recombination]] cause loss of the transistor [[gain (electronics)#Electronics|gain]] (see ''[[#Resultant effects|neutron effects]]''). Components certified as ELDRS (Enhanced Low Dose Rate Sensitive)-free do not show damage with fluxes below 0.01 rad(Si)/s = 36 rad(Si)/h.

====Ionization effects====
Ionization effects are caused by charged particles, including ones with energy too low to cause lattice effects. The ionization effects are usually transient, creating [[glitch]]es and soft errors, but can lead to destruction of the device if they trigger other damage mechanisms (e.g., a [[latchup]]). [[Photocurrent]] caused by [[ultraviolet]] and X-ray radiation may belong to this category as well. Gradual accumulation of [[electron hole|holes]] in the oxide layer in [[MOSFET]] transistors leads to worsening of their performance, up to device failure when the dose is high enough (see ''[[#Resultant effects|total ionizing dose effects]]'').

The effects can vary wildly depending on all the parameters – type of radiation, total dose and radiation flux, combination of types of radiation, and even the kind of device load (operating frequency, operating voltage, actual state of the transistor during the instant it is struck by the particle) – which makes thorough testing difficult, time-consuming, and requiring many test samples.