  Copper-doped zinc sulphide (ZnS:Cu) thin films were synthesized through
pulsed laser ablation in an inert background gas on stationary and rotating
substrates, and a comprehensive opto-electrical characterisation is presented.
The Cu$_x$Zn$_{1-x}$S films demonstrated comparable conductivity and
transparency to other leading p-type transparent conducting materials, with a
peak conductivity of 49.0 Scm$^{-1}$ and a hole mobility of 1.22
cm$^2$V$^{-1}$s$^{-1}$ for films alloyed with an x = 0.33 copper content. The
most conducting films displayed a transparency of 71.8$\%$ over the visible
range at a thickness of 100 nm, and band gaps were found in the range 3.22-3.52
eV, which showed a strong negative correlation with copper content. The effects
of sulphur-rich rapid thermal annealing on the synthesized compound are
reported, with films reliably displaying an increase in conductivity and
carrier mobility. Films grown using a stationary substrate possessed large
spatial thickness distributions and displayed sub-band gap absorption, which is
discussed with respect to inhomogeneous copper substitution. Films deposited at
450$^\circ$C were found to be in the zincblende phase before and after
annealing, with no occurrence of a phase change to wurtzite structure.
