The structure and electrical properties of PbPdO2 thin films with preferred orientation prepared by PLD

We have fabricated PbPdO2 nano-particles and PbPdO2 films with (211) preferred orientation (sample A) and with (002) preferred orientation (sample B), respectively. The structures and physical properties were measured by XRD, Raman, SEM, XPS and AFM. The experimental results indicate that the PbPdO2 films have granular structure with the grain size of about 200 nm and some Pb vacancies exist in both samples. It is found that PbPdO2 with (002) preferred orientation has near zero-gap, while PbPdO2 with (211) preferred orientation has larger band gap. This surface anisotropy band gap is also proved by our first principles band structure calculations. Moreover, one notices that the sample B possesses lower resistivity than sample A, and both samples possess a wide insulator-metal transition temperature (T-MI) with around 370 K.