Formation of high-photoresponsivity BaSi <sub>2</sub> films on glass substrate by radio-frequency sputtering for solar cell applications
Ryota Koitabashi, Taira Nemoto, Yudai Yamashita, Masami Mesuda, Kaoru Toko, Takashi Suemasu
Abstract
Abstract The formation of high-photoresponsivity semiconducting films composed of earth-abundant elements on a SiO 2 substrate is of particular importance for large-scale deployment of solar cells. We investigated the deposition of high-photoresponsivity BaSi 2 films by radio-frequency sputtering on indium-tin-oxide (ITO), Ti, or TiN electrodes formed on a SiO 2 substrate. Raman spectroscopy and x-ray diffraction measurements revealed the formation of randomly oriented polycrystalline BaSi 2 films only on TiN/SiO 2 substrates at 570 °C–650 °C. In contrast, impurity phases such as Ba oxides and TiSi 2 were included when ITO and Ti layers were used, respectively. The photoresponsivity of the BaSi 2 films on TiN electrodes reached 1.1 A W −1 at a wavelength of 790 nm under a bias voltage of 0.5 V applied between the front ITO and bottom TiN electrodes. This value is equivalent to the highest photoresponsivity ever achieved for BaSi 2 epitaxial films on Si(111) substrates by molecular beam epitaxy.