Comparison of hot-carrier relaxation in quantum wells and bulk GaAs at high carrier densities

An investigation of the hot-carrier relaxation in GaAs/(Al,Ga)As quantum wells and bulk GaAs in the high-carrier-density limit is presented. Using a time-resolved luminescence up-conversion technique with {le}80-fs temporal resolution, carrier temperatures are measured in the 100-fs-to-2-ns range. Our results show that the hot-carrier cooling rates in the quantum wells are significantly slower than in the bulk for carrier densities greater than 2{times}10{sup 18} cm{sup {minus}3}. A comparison is made with previous publications to resolve the confusion concerning the difference in cooling rates in quasi-two- and three-dimensional systems.