Preparation of Sn doped In2O3 multilayer films on n-type Si with optoelectronics properties improved by using thin Al–Cu metals interlayer films

Abstract

High-performance transparent conductive Sn doped In2O3/Al–Cu/Sn doped In2O3 (ITO/Al–Cu/ITO) multilayer films were prepared by radio frequency magnetron sputtering of ITO and direct current magnetron sputtering of aluminium Al and copper Cu on n-type Silicon (Si) substrate. The as-deposited and post annealed (400–600 °C) multilayer films microstructural, topological and morphological, optical and electrical properties were investigated. Structural analysis shows an amorphous structure for as-deposited film in spite of the inclusion of thin Al–Cu metals interlayer whereas cubic bixbyite polycrystalline structure was obtained by the annealed films. The films surface properties demonstrate an enhanced surface smoothness and grain size with increasing temperature. The films optimal optoelectronic properties were obtained at 600 °C, yielding a high optical transmittance of 89.2% at 480 nm wavelength, a good sheet resistance of 3.14 Ω/sq with a reduced electrical resistivity of 2.2 × 10−5 Ω-cm. According to the figure of merit (FOM), the film annealed at 600 °C exhibited a remarkable enhancement with a FOM value of 101.56 × 10−3 Ω−1. Current-voltage characteristics results showed an excellent n-Si/ITO/Al–Cu/ITO ohmic contact at 600 °C which can be a promising transparent conductive front window contact on silicon solar cells application.