Abstract
A new double modulation method for photo‐Hall mobility measurements on high impedance photoconductors is described. The magnetic field is modulated by rotating the sample in the field and the density of charge carriers is modulated by chopping the light beam which induces photoconductivity. The Hall signal is detected at the sum frequency of the two modulations and a clear distinction in phase and frequency between the Hall signal and different error signals is obtained. The method has been tested by measuring the Hall mobility of electrons in γ‐irradiated KCl. μH=1.0 exp(646/T) cm2·V−1·sec−1 with μH=9.0 cm2·V−1·sec−1 at 300 K.