The highest recorded photoresponsivity in polycrystalline GaAs films on glass has been updated by precisely controlling the growth temperature of GaAs on a Ge seed layer formed by Al-induced layer exchange. X-ray diffraction and electron backscatter diffraction analyses showed that large-grained (>100 mu m) GaAs (111) films epitaxially grew from the Ge layer above 510 degrees C. According to energy dispersive x-ray and Raman spectra, 550 degrees C was the optimum growth temperature that allowed for the growth of high-quality GaAs film with a stoichiometric composition. Reflecting the high crystallinity, the internal quantum efficiency reached 90% under a bias voltage of 0.3 V. Low-temperature GaAs films grown on inexpensive substrates will make the development of advanced solar cells that achieve both high efficiency and low cost possible. (c) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).