Temperature effects in semiconductor quantum dot lasers

Self-assembled quantum dots (QDs) of highly strained InAlAs have been grown by molecular beam epitaxy (MBE) in separate confinement p-i-n heterostructres on (001) GaAs substrates. At low temperatures, the lasing threshold currents for red-emitting QD lasers are found to be more temperature-independent than for quantum well (QW) lasers. At higher temperatures, the temperature dependence of the threshold currents is governed mainly by the depth of the separate confinement region which was designed to obtain QD lasers capable of room temperature emission with simple broad area laser devices having external efficiencies of ∼13% at low temperatures.