Flexible Amorphous GeSn MSM Photodetectors

We demonstrate amorphous Ge 0.92 Sn 0.08 surface illuminated metal-semiconductor-metal (MSM) photodetectors on flexible substrates for visible wavelength. Photodetection at 633 nm is achieved with an I-V response up to 10 -4 A for a 2 V bias voltage. Different evaporation rate effects on the amorphous GeSn MSM photodetector are examined. Bending/strain effects on device performance were studied by evaluating the current density versus voltage characteristics. Amorphous GeSn thin film deposition on polyethylene terephthalate flexible substrate and Ni/Au-GeSn-Ni/Au MSM photodetector finger pattern deposition were performed via thermal evaporation. Photocurrent and dark current densities of amorphous GeSn MSM photodetectors were obtained at 1.36 A/cm 2 and 0.24 A/cm 2 , respectively, where the photocurrent to dark current contrast ratio was found to be equal to 5.6. We also examined the evaporation rate, strain, and bending effect.