Optoelectronic devices based on MoTe$_{\mathrm{2}}$ p-n junction.

2D transition metal dichalcogenides (2D-TMD), such as MoS$_{\mathrm{2}}$, have been verified with many remarkable physical properties, which include an indirect to direct band transition as a function of thickness and a valley dependent spin polarization. One of the 2D-TMD family members, 2H-MoTe$_{\mathrm{2}}$ has been shown to be a direct bandgap semiconductor as a monolayer and bilayer with a near infrared (NIR) bandgap of about 1.1eV. However, optoelectronic devices based on MoTe2 were so far not experimentally demonstrated. Here, we will present a high on-off ratio MoTe$_{\mathrm{2}}$ p-n junction enabled by a hexagonal boron nitride encapsulation technique. Our study of the MoTe$_{\mathrm{2}}$ p-n junction devices sheds light on designing efficient NIR optoelectronic devices such as photodetectors and energy harvesting cells and light emitters.