Fabricating In-Plane MoTe2 p-n Homojunction Photodetector Using Laser-Induced p-Type Doping

Abstract

The p-n homojunction devices based on 2-D-layered materials (2DLMs) with unusual physical characteristics are gaining extensive research on their use in photodetectors. However, the current fabrication of p-n homojunction devices based on 2DLMs needs a complex doping method. In our work, the laser-irradiation method is a simple and straightforward selective p-type doping technique for the 2-D semiconductor molybdenum ditelluride (MoTe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). The laser-oxidized product MoO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> is responsible for p-type doping in MoTe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The laser-irradiation technique has been used to directly write an in-plane MoTe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> p-n homojunction device, where the laser-scanned region is p-doped and the neighboring region is electrically n-doped by applying a positive back-gate voltage. The MoTe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> p-n homojunction device has been used as a photodetector, which shows a high photoswitching ratio of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> under the illumination of 633 nm at 6.5 μW and a short photoresponse time of 232 μs. The selective p-doped technique using a laser-irradiation method can be used in future logic circuits based on 2-D materials.