Hall Mobility of Slow Electrons in AgCl and the Effects of Crystal Purity

The mobility of carriers in AgCl was investigated over the temperature range 4 to 100 °K by a photo‐Hall technique. The Hall mobility of slow electrons is shown to be very dependent upon sample purity at low temperatures. Mobilities in excess of 30000 cm 2 /Vs were obtained in very high purity zone refined specimens. Special attention was given to the lattice scattering range of mobility above 40 °K in the pure crystals. Hall and drift mobility values for electrons are in reasonable agreement. Although the optical phonon scattering appears to dominate, there is an evidence that the Debye temperature is somewhat lower than expected. It is suggested that this might be due to a finite spread in the long wavelength longitudinal optical frequency. It is believed that the scattering due to the acoustical mode of lattice vibrations becomes of considerable importance in high‐purity crystals in an intermediate temperature range (between 34 °K and 12 °K) even for slow electrons.