Photoluminescence and photocurrent measurement in monolayer MoTe$_{2}$

2D transition metal dichalcogenides (2D-TMD), such as MoS$_{2}$, WS$_{2}$, WSe$_{2}$, MoSe$_{2}$, have been verified with many remarkable physical properties including the indirect to direct band transition and valley dependent spin polarization. As one of the 2D-TMD family member, monolayer 2H-MoTe$_{2}$ is proved to be a direct bandgap semicoductor with strong spin orbital interaction and a significantly low bandgap $\sim$ 1.10eV. However, the effect of the enhanced coulomb interaction arising from reduced dielectric screening in monolayer MoTe$_{2}$ has yet to be experimentally demonstrated. Here we employ the near infrared (NIR) photoluminescence and photocurrent measurement to study the quasi-particle interactions at different carrier concentration. This study sheds light on manipulating excitons in MoTe$_{2}$ and designing highly efficient NIR optoelectronic devices.