Effect of ITO Capping Layer on Interface Workfunction of MoOx in ITO/MoOx/SiO2/Si Contacts

Effects of an ITO capping layer on the interface workfuncion of MoO x was studied for an ITO/MoO x /SiO2/Si structure device from the viewpoint of the behavior of In atoms. The workfunction of MoO x at the MoO x /SiO 2 interface, which were extracted by capacitance-voltage (C-V) analysis, was largely different from the bulk MoO x film in its value and post-deposition forming gas annealing (PDFGA) temperature dependency. The interface workfunctoin decreased by 0.13 and 0.35 eV by 200 and 400 °C PDFGA, respectively, while bulk workfunction decreased by only 0.1 eV by 400 °C PDFGA. A secondary ion mass spectroscopy (SIMS) analysis showed that In atoms were penetrated from the ITO layer into the MoO x layer by PDFGA. The concentration of In near the MoO x /SiO 2 interface increased from ∼1019 cm−3 for the as-grown ITO sample to ∼1020 cm−3 for the sample with 400 °C PDFGA. The increase in the In concentration near the MoO x /Japan>SiO 2 interface is a possible cause to decrease the interface workfunction.