Atomic layer deposition of ultrathin indium oxide and indium tin oxide films using a trimethylindium, tetrakis(dimethylamino)tin, and ozone precursor system

Abstract

Indium oxide (IO) and indium tin oxide (ITO) are widely used in optoelectronics applications as a high quality transparent conducting oxide layer. A potential application of these coatings is for enhancing the electrical properties of spacecraft thermal radiator coatings, where dissipating built-up static charge is crucial. In this work, the authors investigated the thickness-dependent electrical and optical properties of IO thin films synthesized by atomic layer deposition (ALD) with the aim of finding the optimum condition for coating radiator pigments. Trimethylindium and ozone were used as precursors for IO, while a tetrakis(dimethylamino)tin(IV) source was used for Sn doping to produce ITO. As-deposited IO films prepared at 140 °C resulted in a growth per cycle of 0.46 Å/cycle and film resistivity as low as 1.4×10−3 Ω cm. For the case of ITO thin films, an ALD process supercycle consisting of 1 Sn + 19 In cycles is shown to provide the optimum level of Sn doping corresponding to 10 wt. % widely reported in the literature.