Barrier-controlled thermalization inIn0.53Ga0.47As/InP quantum wells

We have studied the influence of the barrier thickness on hot-carrier cooling in Nd-YAG (yttrium aluminum garnet) laser-excited ${\mathrm{In}}_{0.53}$ ${\mathrm{Ga}}_{0.47}$As/InP quantum wells by picosecond-time-resolved spectroscopy. The experiments yield striking differences of the transient carrier temperatures for different barrier thicknesses. For small barrier thicknesses we observe initial carrier temperatures up to 500 K, whereas for large barrier thicknesses the carrier temperatures stay below 120 K. The experimental data can be explained by microscopic calculations of the transient variation of the carrier densities and the thermalization of hot carriers in the quantum well.