Extrinsic luminescence centers in CdI2 crystals doped with PbI2 (10−4 to 1 mol %)

Abstract

We have studied the luminescence properties of PbI2 doped (10−4 to 1 mol %) CdI2 crystals in the temperature range 4.2–90 K and those of 2H- and 4H-PbI2 crystals at 90 K. The results demonstrate that the Pb atoms produce impurity centers in the form of isolated Pb2+ ions and 4H-PbI2 nanocrystals located in the plane of the layers or along linear structural defects of CdI2. The formation of PbI2 nanocrystals was confirmed by atomic force microscopy. We discuss excitonic and electron-hole mechanisms of energy transfer to luminescence centers.