Quantum dot p-i-n structure in an electric field

Time-resolved photoluminescence (PL), steady-state FL, and electroluminesce nce (EL) techniques have been used to characterize the carrier relaxation p rocesses and carrier escape mechanisms in self-assembled InAs/GaAs quantum dot (SAQD) p-i-n structures under reverse bias. The measurements were perfo rmed between 5 K and room temperature on a ring mesa sample as a function o f bias. At 100 K, the PL decay time originating from the II = 1 SAQD decrea ses with increasing reverse bias from similar to 3 ns under flat band condi tion to similar to 400 ps for a bias of -3 V. The data can be explained by a simple model based on electron recombination in the quantum dots (QDs) or escape out of the dots. The escape can occur by one of three possible rout es: direct tunneling out of the distribution of excited electronic levels, thermally assisted tunneling of ground stare electrons through the upper ex cited electronic states or thermionic emission to the wetting layer. (C) 19 99 Academic Press.