Broad-Band Photodetector Based on a Lateral MoTe2 1T-2H-1T Homojunction

The use of a two-dimensional (2D) layered molybdenum ditelluride (MoTe2) nanosheet in electronic devices can be enhanced by transforming its electrode to a metallic phase, forming a 1T-2H-1T heterogeneous structure. This, however, leads to the formation of a junction between the electrode and the channel which can reduce the effectiveness of the device. To address this issue, this paper proposes a novel method of creating 1T-2H-1T MoTe2 optoelectronic devices using oxygen mild plasma preparation. Transmission electron microscopy testing and first-principles calculations have confirmed that this treatment results in the loss of some Te atoms, thus lowering their energy bands and creating metallic properties. The electrical and optoelectronic performance testing at varying temperatures and wavelengths has revealed improved mobility and responsiveness, with a maximum mobility of 30 cm2/V s and a responsivity of 0.6 A/W under a 940 nm laser irradiation, being 25 times higher than the intrinsic one. This research provides an efficient phase engineering technique for the accurate and undamaged fabrication of optoelectronic devices using two-dimensional materials.