In situ transmission electron microscopy study of molybdenum oxide contacts for silicon solar cells

In this study, a molybdenum oxide (MoO${}_x$) and aluminum (Al) contact structure for crystalline silicon (c‐Si) solar cells is investigated using a combination of transmission line measurements (TLM) and in‐situ transmission electron microscopy (TEM). Cross‐sectional high‐resolution TEM (HRTEM) micrographs reveal a ≈2 nm silicon oxide (SiO${}_x$) interlayer at c‐Si/MoO${}_x$ interface in the as‐deposited state, indicating that formation of SiO${}_x$ occurs during deposition of MoO${}_x$. Moreover, oxygen diffusion takes place from MoO${}_x$ toward Al resulting in the formation of a ≈2–3 nm aluminum oxide (AlO${}_x$) interlayer at the MoO${}_x$/Al interface. Overall, it is observed that MoO${}_x$/Al contact is relatively stable upon annealing up to 200 °C and still retains ohmic transport with sufficiently low contact resistivity. (© 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)