Preparation and characterization of cobalt-doped iron pyrite(FeS_2) thin films

Iron pyrite (FeS_2) incorporated with cobalt dopant varying from 2%to 6%atomic ratio,was synthesized by using an aqueous hydrothermal process.The thin films of Co-doped FeS_2were fabricated by a vacuum thermal evaporation of synthesized FeS_2powder.The structural,electrical and optical properties of as-deposited and sulfurized films were investigated.The X-ray diffraction results indicated that the synthesized powder and thin films showed a cubic pyrite structure.The crystallinity of FeS_2was slightly degraded by the doping of cobalt.The dependence of thin-film resistance on the temperature indicated an increase of activation energy until 3 at%cobalt doping and then decreased the resistance with the increase of cobalt concentration.Hall effect measurements showed that the Co-doped samples have n-type conduction except for the 2 at%.The carrier concentration was in the order of 10~(18)cm~(-3),whereas,the carrier mobility decreased from 6.52 cm~2/V.s to 4.3 cm~2/V.s with the increase of cobalt dopant.The photosensitivity of undoped and cobalt-doped FeS_2films was measured under AM 1.5G and NIR light.The sulfurized films showed a higher photoresponse than the asdeposited films for both visible and IR lights.