Composition Dependent Majority Charge Carriers in Cobalt Iron Sulfide (Co $_{\mathrm{\mathbf{x}}}${Fe}$_{\mathrm{\mathbf{1-x}}}${S}$_{\mathrm{\mathbf{2}}}$) Pyrite Nanocrystals

We report the hot-injection colloidal chemical synthesis, and characterization of cobalt (Co) doped iron pyrite (FeS$_{\mathrm{2}})$ nanocrystals (NCs). The synthesized alloyed Co$_{\mathrm{x}}$Fe$_{\mathrm{(1-x)}}$S$_{\mathrm{2}}$ pyrite NCs have been characterized by using X-ray diffraction(XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman, and UV-Vis-NIR spectroscopy. We discuss the electronic properties such as resistivity, mobility, carriers concentration of the NC thin films. Based on the hot-probe and Hall measurements, the iron pyrite (FeS$_{\mathrm{2}})$ NC thin films are p-type, and on doping these iron pyrite NCs with Co, the majority charge carriers changes from p-type to n-type in between the Co concentration of 16\% to 21\%.