  We systematically investigated the modulation of heat transport of
experimentally accessible two-dimensional (2D) group-III chalcogenides by
firstprinciples calculations. It was found that intrinsic thermal conductivity
(kappa) of chalcogenides MX (M = Ga, In; X = S, Se) were desirable for
efficient heat dissipation. Meanwhile, we showed that the long-range anharmonic
interactions played an important role in heat transport of the chalcogenides.
The difference of kappa among the 2D group-III chalcogenides can be well
described by the Slack model and can be mainly attributed to phonon group
velocity. Based on that, we proposed three methods including strain
engineering, size effect and making Janus structures to effectively modulate
the kappa of 2D group-III chalcogenides, with different underlying mechanisms.
We found that tensile strain and rough boundary scattering could continuously
decrease the kappa while compressive strain could increase the kappa of 2D
group-III chalcogenides. On the other side, the change of kappa by producing
Janus structures is permanent and dependent on the structural details. These
results provide guilds to modulate heat transport properties of 2D group-III
chalcogenides for devices application
