  We report on the first demonstration of p-type doping in large area few-layer
films of (0001)-oriented chemical vapor deposited (CVD) MoS2. Niobium was found
to act as an efficient acceptor up to relatively high density in MoS2 films.
For a hole density of 4 x 1020 cm-3 Hall mobility of 8.5 cm2V-1s-1 was
determined, which matches well with the theoretically expected values. XRD and
Raman characterization indicate that the film had good out-of-plane crystalline
quality. Absorption measurements showed that the doped sample had similar
characteristics to high-quality undoped samples, with a clear absorption edge
at 1.8 eV. This demonstration of p-doping in large area epitaxial MoS2 could
help in realizing a wide variety of electrical and opto-electronic devices
based on layered metal dichalcogenides.
