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

Time-resolved photoluminescence (PL), steady-state FL, and electroluminescence (EL) techniques have been used to characterize the carrier relaxation processes and carrier escape mechanisms in self-assembled InAs/GaAs quantum dot (SAQD) p-i-n structures under reverse bias. The measurements were performed between 5 K and room temperature on a ring mesa sample as a function of bias. At 100 K, the PL decay time originating from the II = 1 SAQD decreases with increasing reverse bias from similar to 3 ns under flat band condition 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 routes: direct tunneling out of the distribution of excited electronic levels, thermally assisted tunneling of ground stare electrons through the upper excited electronic states or thermionic emission to the wetting layer. (C) 1999 Academic Press.