  Inducing electrostatic doping in 2D materials by laser exposure (photodoping
effect) is an exciting route to tune optoelectronic phenomena. However, there
is a lack of investigation concerning in what respect the action of photodoping
in optoelectronic devices is local. Here, we employ scanning photocurrent
microscopy (SPCM) techniques to investigate how a permanent photodoping
modulates the photocurrent generation in MoS2 transistors locally. We claim
that the photodoping fills the electronic states in MoS2 conduction band,
preventing the photon-absorption and the photocurrent generation by the MoS2
sheet. Moreover, by comparing the persistent photocurrent (PPC) generation of
MoS2 on top of different substrates, we elucidate that the interface between
the material used for the gate and the insulator (gate-insulator interface) is
essential for the photodoping generation. Our work gives a step forward to the
understanding of the photodoping effect in MoS2 transistors and the
implementation of such an effect in integrated devices.
