Photoconductivity mechanisms in the magnetic semiconductor euse

Abstract

In the europium chalcogenides, the 4f spin order is strongly coupled to electronic conduction. The results of static and transient photoconductivity measurements in EuSe show that there is thermally activated conduction in the paramagnetic region which increases with increasing magnetic field. These effects are similar to previous dark conductivity measurements in Gd-doped EuSe. The transient photoconductivity measurements show that it is the mobility and not the lifetime which is dependent on temperature and magnetic order. The results are explained using a magnetic impurity state model, MIS, in which spin clusters form around crystal defects. The observed distribution of long photodecay times is associated with relaxation between the MIS on a neutral complex defect and charged defect. The thermally activated conduction may be due to either hopping or quasithermal activation to the conduction band. © 1971 The American Institute of Physics.