Integration of a-IGZO Thin-Film Transistor and Crystalline-Si Interdigitated Back Contact Photovoltaic Cell With 3D Stacking Structure as Self-Powered Solar Switch

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/a-IGZO thin film transistor (TFT) was directly stacked on a crystalline-Si interdigitated back contact (IBC) photovoltaic (PV) cell to create a self-powered solar switch. The a-IGZO TFT and IBC PV cell were integrated into a single chip without an external circuit. This device exhibits switching property induced by illumination. The results show that it can be switched even under a low solar illumination of 300 W/m
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due to the low threshold voltage of the a-IGZO TFT (0.25 V). The ON/OFF current contrast ratio was measured to be ~20 under 1-sun illumination. The fabrication process and characteristics of this device make it suitable and practicable for use as a self-powered solar switch.