Electron Mobility in CdS at High Electric Fields

The Hall mobility of electrons in CdS platelets has been measured at 230°K as a function of the electric field using stationary cathode-adjacent high-field domains in the range of negative differential conductivity. The electron mobility is observed to be field-independent up to 30 kV/cm. Above 30 kV/cm it decreases linearly with the field from its low-field value of about 620 ${\mathrm{cm}}^2$/V sec, to about 300 ${\mathrm{cm}}^2$/V sec at 70 kV/cm, indicating scattering of hot electrons with optical phonons.