Visible quantum dots under reversed bias

Abstract

Time-resolved photoluminescence (PL), steady-state PL, and electro-luminescence techniques have been used to characterize the carrier relaxation processes and carrier escape mechanisms in a self-assembled AlInAs quantum dots (SAQD) p-i-n laser structure under reversed 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 SAQD decreases with increasing reversed bias from approximately 450 ps under flat band condition to approximately 150 ps for biases of -4 V. The data can be explained by a simple model based on electron recombination in the quantum dots or escape our of the dots. The escape can occur by one of three possible routes: direct tunneling out of the distribution of electron excited state level, thermally assisted tunneling of ground state electrons through the upper electron excited states or thermionic emission to the wetting layer.