Investigating the\nLocal Bonding Structure of Amorphous\nZinc Tin Oxide to Elucidate the Effect of Altering the Intercation\nRatio

In this paper, the\nlocal bonding structure in amorphous\nzinc tin\noxide (a-ZTO) is probed using a combination of XANES and EXAFS techniques\nat the Zn and Sn K-edges to gain insight into charge carrier generation\nin the material. a-ZTO is prepared using two growth methods; spray\npyrolysis and magnetron sputtering. It is seen that a-ZTO grown by\nmagnetron sputtering shows no changes in the chemical environment\nas the cation ratio is varied; meanwhile, XANES analysis of spray\npyrolysis grown samples shows alterations to spectra likely due to\nthe effects caused by different precursors. Although a slight shift\nin Sn–O bond length is visible between magnetron sputtered\nand spray grown samples, no correlation could be discerned between\nbond length and variation in cation ratio. It is concluded that a-ZTO,\nwhile amorphous over longer ranges, is locally composed of ZnO and\nSnO<sub>2</sub> “building blocks”. An alteration in\nthe cation ratio changes the hybridization at the conduction band\nminimum, resulting in the observed variation in the mobility, charge\ncarrier concentration, and bandgap.