Electron Spin Resonance Studies of Shallow Donors in CdS

Abstract

The electric spin resonance of donor electrons was investigated in the temperature range from 1.4 K to 4.2 K in several types of CdS, i.e. the undoped crystals grown from the vapour phase and grown by the melt, the crystals doped with chlorine, iodine, oxygen, and both chlorine and neodymium. In Cl-doped CdS and also I-doped CdS, the also I-doped CdS, the variation of the line width with the excess donor concentration and the temperature indicated that the motional narrowing effect due to the hopping motion of the donor electron occurred on the line width in a certain donor concentration range. In Cl-doped CdS the additional line broadening due to the shortening of the relaxation time occurred at the concentrations above 7×16 16 cm -3 . The hyperfine splitting of the donors Cl and I was estimated by the line width extraporated to the lower limit of their concentration. In other crystals, the nature of the donor is discussed on the basis of the results of ESR measurements and optical emission ones. The electric field effect on the donor resonance was examined at 1.4 K, but no change in the resonance line was observed in the static electric field up to 3.29 kV/cm.