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▼ [21p-B202-3] Improved Photovoltaic Properties of Few-layer WS0.3Se1.7/WOx Lateral p+-n Junctions
Keywords:2D WS2-xSex, Lateral p+-n junction, Solar cell
We investigated the photovoltaic properties of the lateral p+-n junction composed of few-layers WS0.3Se1.7 including chalcogenide vacancies generated by the atmospheric-pressure plasma followed by laser irradiations via field-effect transistor structures. The lateral p+-n junction was formed on the few-layer WS0.3Se1.7 by the He/O2 plasma followed by the laser irradiations with different excitation wavelengths using a shadow metal mask. A laser irradiation of 420 nm promoted the generation of sulfur vacancies of WS0.3Se1.7 layers and the improved rectification behavior of current-voltage characteristics in the lateral p+-n junction. They also show a photovoltaic effect with a short-circuit current (ISC) of order of 10-9 A and an open-circuit voltage of 0.788 V. Further increase of ISC of an order of 10-6 A was obtained by inserting a silver mirror layer between the dielectric layer of Al0.73Ti0.26Oy (ATO) and the c-Si substrate which originate from the enhanced multiple reflection in the Fabry-Perot cavity. Ammonium tetrathiotungstate (NH4)2WS4 and mixture of N-metyl-2-Pyrrolidone (NMP) (55 wt.%), methylamine (30 wt.%), and 2-aminoethanol (15 wt.%) were used as a precursor and solvent. The WSx few-layers with a thickness of 3-5 nm were fabricated by spin-coat at 500 rpm for 10 s followed by 4000 rpm for 60 s on thermally grown (th-) SiO2 (285 nm) and mist CVD grown ATO (50-100 nm) coated c-Si substrates. Subsequently, the selenization of WSx was executed at Tf of 600 °C for 20 minutes.