Micrometer-thin SOI Sensors for E-Skin Applications

Ultra-thin silicon-on-insulator-based sensors are presented, featuring a thickness of less than 20 μm, as new integrable items for wearable physical and physiological ultra-low-power applications. Depending on the Si thickness, the back contact realization and the bias conditions, they can be optimized for thermal sensing or optical sensing in the UV-VIS light band. A lateral PIN diode with a transparent graphene back gate shows a maximum responsivity of 0.18 A/W at 390 nm wavelength, and a high sensitivity of ~2.28 mV/°C at fixed 0.01 μA low bias current, whereas a vertical PN strip diode with an Al back contact extends the optical responsivity to the visible range (with e.g. 0.24 A/W at 555nm wavelength when biased at -2 V) and achieves a high-temperature sensitivity using constant reverse voltage method.