ZnO is expected to become a DMS when it is doped with
a first-row transition metal. DMS materials, which also
include other II-VI or III-V semiconductors (e.g., GaN,
ZnS, GaAs) doped with transition metals, are currently the
subject of intense research, principally for their potential use
in spin-based electronic, or “spintronic”, devices, where the
spin of the electron is utilized in addition to its charge. A
few prototypical spin-based light-emitting diodes (LEDs)
have been fabricated; these devices employ a series of
DMS quantum dots embedded between the p- and n-type
layers of the LED. The ferromagnetic behavior of the DMS
causes the emitted light to be circularly polarized. Most ZnO
DMS research is done on thin films or quantum dots,
with very few reports on transition-metal-doped ZnO nanowires.
Most of these studies employ high-temperature, vaporphase
synthetic methods, and their results have been
reviewed elsewhere.5