In-Plane 2H-1T′ MoTe₂ Homojunctions Synthesized by Flux-Controlled Phase Engineering

The fabrication of in-plane 2H-1T′ MoTe₂ homojunctions by the flux-controlled, phase-engineering of few-layer MoTe₂ from Mo nanoislands is reported. The phase of few-layer MoTe₂ is controlled by simply changing Te atomic flux controlled by the temperature of the reaction vessel. Few-layer 2H MoTe₂ is formed with high Te flux, while few-layer 1T′ MoTe₂ is obtained with low Te flux. With medium flux, few-layer in-plane 2H-1T′ MoTe₂ homojunctions are synthesized. As-synthesized MoTe₂ is characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. Kelvin probe force microscopy and Raman mapping confirm that in-plane 2H-1T′ MoTe₂ homojunctions have abrupt interfaces between 2H and 1T′ MoTe₂ domains, possessing a potential difference of about 100 mV. It is further shown that this method can be extended to create patterned metal–semiconductor junctions in MoTe₂ in a two-step lithographic synthesis. The flux-controlled phase engineering method could be utilized for the large-scale controlled fabrication of 2D metal–semiconductor junctions for next-generation electronic and optoelectronic devices.