Spectroscopy and hot electron relaxation dynamics in semiconductor quantumwells and quantum dots

Photoexcitation of a semiconductor with photons above the semiconductor ban d gap creates electrons and holes that are out of equilibrium. The rates at which the photogenerated charge carriers return to equilibrium via thermal ization through carrier scattering, cooling by phonon emission, and radiati ve and nonradiative recombination are important issues, The relaxation proc esses can be greatly affected by quantization effects that arise when the c arriers are confined to regions of space that are small compared with their deBroglie wavelength or the Bohr radius of bulk excitons. The effects of s ize quantization in semiconductor quantum wells (carrier confinement in one dimension) and quantum dots (carrier confinement in three dimensions) on t he respective carrier relaxation processes are reviewed, with emphasis on e lectron cooling dynamics. The implications of these effects for application s involving radiant energy conversion are also discussed.