Influence of precursor nature on the thermal growth of Tin–Indium oxide layers by MOCVD

Abstract

We investigate three indium and two tin precursors for metalorganic chemical vapor deposition to highlight their influence on the resulting indium oxide or tin doped indium oxide (ITO) layers. Selected indium precursors are In(acac)3, In(tmhd)3 and InMe2OtBu, and tin precursors are DBTDA and Sn(acac)2. Acetyl acetonate ligand is identified to induce an organic contamination in the In2O3 and ITO layers when depositions are performed with In(acac)3 or Sn(acac)2 as precursor.The growth kinetic is also investigated. InMe2OtBu presents a higher deposition rate and reactivity; besides the grown films crystallize at lower temperature as compared with the two other indium precursors. Moreover, it is the only studied indium precursors which allow synthesizing In2O3 and ITO layers without oxygen addition. Depending on the atmosphere, layers synthesized with InMe2OtBu present different morphology. In particular, without oxygen addition, a (222) preferential orientation is detected by X-ray diffraction and correlated to a morphology composed of bundles of nanowires as evidenced by transmission electronic microscopy.Concerning tin doping in the ITO layer, incorporation is more efficient when using DBTDA than Sn(acac)2 and when combined with InMe2OtBu than with In(tmhd)3 and In(acac)3.