In-layer conductivity and photoconductivity in MnPSe3, CdPSe3, and CdPS3

Electrical properties of single crystals of the MnPSe3, CdPSe3, and CdPS3 layered compounds have been investigated by in-layer dc conductivity and photoconductivity measurements as a function of temperature. The observed dc conductivity dependence exhibits a semiconductor behavior for all three compounds in spite of their high resistivity values. At high temperatures the dc conductivity of all three compounds shows an Arrhenius temperature dependence, while photoconductivity is thermally activated only for MnPSe3 and almost temperature independent for CdPSe3 and CdPS3. These results, interpreted in terms of the simplified energy-band schemes existing for CdPX3 and MnPSe3, have allowed us to identify the conduction mechanisms and to deduce more information about the distribution of the electronic states in the gap region.