  We investigate a vertically-stacked hybrid photodiode consisting of a thin
n-type molybdenum disulfide (MoS$_{2}$) layer transferred onto p-type silicon.
The fabrication is scalable as the MoS$_{2}$ is grown by a controlled and
tunable vapor phase sulfurization process. The obtained large-scale p-n
heterojunction diodes exhibit notable photoconductivity which can be tuned by
modifying the thickness of the MoS$_{2}$ layer. The diodes have a broad
spectral response due to direct and indirect band transitions of the nanoscale
MoS$_{2}$. Further, we observe a blue-shift of the spectral response into the
visible range. The results are a significant step towards scalable fabrication
of vertical devices from two-dimensional materials and constitute a new
paradigm for materials engineering.
