One paper this week, because real life continues to kick my butt.
cond-mat/0701119 - Minot et al., Single quantum dot nanowire LEDs
This is a really nice example of how impressively refined semiconductor nanowire growth has become. By carefully varying the growth conditions and precursors, the composition of growing InP nanowires can be tailored to form a single wire with a p-doped InP lead, an n-doped InP lead, and an interaction region in between formed from InP(1-x)As(x), which has a smaller bandgap than either of the InP segments. The result is a single nanowire LED, potentially well-suited for single-photon emission experiments and the like. Since the whole active region is vastly smaller than the relevant wavelength, the surrounding medium is essentially free space, and screening is comparatively poor in such tiny 1d structures, quantum confinement and charging effects both play a role. Very pretty.