  Utilizing spin or valley degree of freedom is one of the promising approaches
to realize more energy-efficient information processing. In the 2D transition
metal dichalcogenide, the spin/valley current can be generated by utilizing the
circular photogalvanic effect (CPGE), i.e., the generation of photocurrent by a
circularly polarized light. Here we show that an in-plane electric field at
MoS2/WSe2 heterostructure-electrode boundary results in an electrically tunable
circular photogalvanic effect (CPGE) under optical excitation with normal
incidence. The observed CPGE can be explained by the valence band shift due to
the in-plane electric field and different effective relaxation times between
hole and electron combined with the valley optical selection rule. Furthermore,
we show that the CPGE can be controlled by changing the Fermi level using an
out-of-plane electric field. Such phenomena persist even at room temperature.
This finding may facilitate the utilization of 2D heterostructure as an
opto-valleytronics and opto-spintronics device platform.
