  The rate at which excited charge carriers relax to their equilibrium state
affects many aspects of the performance of nanoscale devices, including
switching speed, carrier mobility and luminescent efficiency. Better
understanding of the processes that govern carrier relaxation therefore has
important technological implications. A significant increase in carrier-carrier
interactions caused by strong spatial confinement of electronic excitations in
semiconductor nanostructures leads to a considerable enhancement of Auger
effects, which can further result in unusual, Auger-process-controlled
recombination and energy-relaxation regimes. Here, we report the first
experimental observation of efficient Auger heating in CdSe quantum rods at
high pump intensities, leading to a strong reduction of carrier cooling rates.
In this regime, the carrier temperature is determined by the balance between
energy outflow through phonon emission and energy inflow because of Auger
heating. This equilibrium results in peculiar carrier cooling dynamics that
closely correlate with recombination dynamics, an effect never before seen in
bulk or nanoscale semiconductors.
