Resumo:
Semiconducting molybdenum disulfphide has emerged as an attractive material for novel nanoscale
optoelectronic devices due to its reduced dimensionality and large direct bandgap. Since optoelectronic
devices require electron-hole generation/recombination, it is important to be able to fabricate ambipolar
transistors to investigate charge transport both in the conduction band and in the valence band. Although
n-type transistor operation for single-layer and few-layer MoS2 with gold source and drain contacts was
recently demonstrated, transport in the valence band has been elusive for solid-state devices. Here we show
that a multi-layer MoS2 channel can be hole-doped by palladium contacts, yielding MoS2 p-type transistors.
When two different materials are used for the source and drain contacts, for example hole-doping Pd and
electron-doping Au, the Schottky junctions formed at the MoS2 contacts produce a clear photovoltaic effect.
