Zinc oxide has been an attractive material not only for the fabrication of
light emitting diodes (LEDs), but also for the harvesting of both solar
and mechanical energy. In particular, p-type ZnO nanowires exhibit
superior performance in optical and electrical devices due to the
enhancement in their semiconducting, piezoelectric, and photoluminescent
properties. However, there has been a substantial challenge in achieving
stable p-type doping in ZnO; there has also been a need to control ZnO
nanowire band gaps for LED applications.
To accomplish these goals, Wang and co-workers use catalyst–free pulse
laser deposition (PLD) for the growth of phosphorus–doped Zn1-xMgxO
nanowire arrays. The chemical composition, dimension, band gap, and
conductivity type can be controlled through stepped variations in
experimental conditions. For example, the blue shift of photoluminescence
peaks suggests that the optical band gap of Zn1-xMgxO nanowires increases
linearly as the Mg content increases. Furthermore, phosphorus–doped
Zn1-xMgxO nanowires display both a positive piezoelectric output around
60 mV as well as temperature–dependent photoluminescence.
In conclusion, systematic fabrication of p-type phosphorus-doped alloyed
Zn1-xMgxO nanowire arrays has been demonstrated using a PLD approach,
yielding controllable morphologies and properties. Phosphorus doping can
yield p-type conductivity for high-output nanogenerators as well as for
other optical and electrical applications. Moreover, by incorporating Mg
into the ZnO matrix, the band gap can be precisely tuned in order to
facilitate LED applications.