Characteristics of the electron traps produced by electron irradiation inn-type germanium

The free energies of ionization, the emission rates, and the cross sections for electron trapping have been measured for the four majority carrier traps which are produced in $n$-type germanium by electron irradiation at room temperature and which are stable at this temperature. These traps, labeled $E_1$, $E_2$, $E_4$, and $E_5$, which exhibit an emission rate of 140 ${\mathrm{s}}^{-1\mathrm{}}$ at 145, 200, 185, and 170 K, are situated at 260, 410, 380, and 370 meV below the conduction band, respectively. The variations of the electron-capture cross sections versus temperature, characterized by the following activation energies: 65, 120, 80, and 50 meV, respectively, indicate that nonradiation recombination occurs through multiphonon emission. From the values of the free energies of ionization and from the variation of the emission rates with temperature, the enthalpies and entropies of ionization have been deduced.