摘要：The strong correlation between grain size and photoresponsivity in polycrystalline GaAs films on glass was experimentally demonstrated using Ge seed layers with a wide range of grain sizes (1‒330 μm). The crystal evaluations using Raman spectroscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy revealed that 500-nm-thick GaAs films epitaxially grown from the Ge seed layers at 550 °C inherited the grain boundaries and crystal orientations in Ge. With increasing grain size, the photoresponsivity corresponding to GaAs increased from 0.01 to 3 A W
−1 under a bias voltage of 0.3 V. The maximum value approached that of the GaAs film formed simultaneously on a single-crystal Ge wafer, indicating the high potential of the large-grained GaAs film. Knowledge gained from this study will be essential for designing advanced solar cells based on polycrystalline III–V compound semiconductors using inexpensive substrates.
