  The increasing technological control of two-dimensional materials has allowed
the demonstration of 2D lateral junctions, which display unique properties that
might serve as the basis for a new generation of 2D electronic and
optoelectronic devices. Notably, the chemically doped MoS$_2$ homojunction, the
WSe$_2$-MoS$_2$ monolayer and MoS$_2$ monolayer/multilayer heterojunctions,
have been demonstrated. Here we report the investigation of 2D lateral junction
electrostatics, which differs from the bulk case because of the weaker
screening, producing a much longer transition region between the space charge
region and the quasi-neutral region, making inappropriate the use of the
complete-depletion approximation. For such a purpose we have developed a method
based on the conformal mapping technique to solve the 2D electrostatics, which
is widely applicable to every kind of junctions, giving accurate results for
even large asymmetric charge distribution scenarios.
