  The shortcomings of mono-component systems, e.g., the gapless nature of
graphene, the lack of air-stability in phosphorene, etc. have drawn great
attention toward stacked materials expected to show interesting electronic and
optical properties. Using the tight-binding approach and the Green's function
method, we investigate the electronic properties of armchair-edged lateral
phosphorene/graphene heterostructures, which are either
semiconductor/semiconductor or semiconductor/metal heterostructures, depending
on the width of graphene ribbon. It is found that the system is narrow-gapped,
and the bandgap can be modulated by tuning the size of the domains. Besides,
the analysis of the bandgap variation against the width of the component
phosphorene ribbon indicates that, in semiconductor/metal heterostructure,
phosphorene ribbon does not induce any electronic state near the Fermi level,
suggesting that the suppressed electron transport should be attributed to the
hole transfer across the interface. Furthermore, we show that the transverse
electric field can significantly diversify the electronic behavior of the
heterostructure, i.e., the heterostructure undergoes the semiconductor-metal
phase transition. Moreover, tuning the transverse electric field yields an
intriguing possibility that the system can undergo a topological phase
transition from a band insulator to a topological insulator.
