Machine Learning-Assisted Multi-Wavelength Perception Enabled by Ultrathin, Large-Area Printed Indium Oxysulfide Phototransistors

We present a method of fabricating uniform, large area indium oxysulfide ($\mathrm{InO}_{\mathrm{x}} \mathrm{S}_{\mathrm{y}}$) films using a vacuum-free continuous liquid metal printing method (CLMP) and sulfurization process for high-performance multi-wavelength photodetection. CLMP enables rapid printing of wide area ($\gt10 \mathrm{~cm}^{2} / \mathrm{s}$) metal oxide films of single nmscale thickness at process temperatures just above $150^{\circ} \mathrm{C}$, which can be partially converted to metal oxy-chalcogenide thin films at back-end-of line (BEOL) process temperatures. Phototransistors fabricated from 16 nm-thick $\mathrm{InO}_{\mathrm{x}} \mathrm{S}_{\mathrm{y}}$ achieved responsivities as high as $280 \mathrm{~A} / \mathrm{W}$ and respond to wavelengths as long as 630 nm, enabling both classification of multiple wavelengths and readout of intensity assisted by machine learning models.