Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The photoconduction in CdS single crystals is investigated up to generation rates of 5 × 10<jats:sup>28</jats:sup> cm<jats:sup>−3</jats:sup> s<jats:sup>−1</jats:sup> for one‐photon and two‐photon excitation by a giant pulse ruby laser. The initially generated hot carriers thermalize into excitons within about 10<jats:sup>−13</jats:sup> s. At 1.8 K a strongly supralinear dependence of the photoconduction on excitation intensity (power 4 for two‐photon excitation and power 2 for one‐photon excitation) indicates that the free carriers observed by the photoconduction are generated by inelastic exciton–exciton scattering (P‐process). At higher temperatures (80 K, 300 K) the free electrons are due mainly to dissociation of the excitons. At generation rates higher than 10<jats:sup>27</jats:sup> cm<jats:sup>−3</jats:sup> s<jats:sup>−1</jats:sup> up to the temperature of 80 K the condensation of the excitons into an electron‐hole plasma is observed. The phase transition is accompanied by a discontinuous increase in conductivity, strong fluctuations at the transition point, and a square‐root dependence of the photoconductivity at higher excitation intensities.</jats:p>