Transient Magnetoresistance of Photoelectrons in Cadmium Sulfide

Abstract

Magnetoresistance of photoelectrons in CdS has been measured in a transient condition as a function of magnetic field, electric field and of their directions relative to the crystal axis in the temperature range from 1.9°K to 78°K by using pulsed light and a pulsed electric field. A difference is observed between E||c and E⊥c in low field transverse magnetoresistance at 1.9°K and 4.2°K but not at 78°K, indicating a dominant contribution of anisotropic scattering by the piezoelectric field at low temperatures. The longitudinal magnetoresistance is found to be almost zero. The transverse magnetoresistance is observed to increase according to the H² law but deviates from it at high magnetic fields. The low magnetic field magnetoresistance decreases above a certain critical electric field where the photoresponse does not obey the Ohm’s law because of a hot electron effect. The hot electrons are found to be cooled by application of a magnetic field.