Electroluminescence of GaSb/GaAs Quantum Dots

GaSb/GaAs quantum dots (QDs) exhibit the type-II band alignment where the spatial separation between electron and hole wave functions occurs. The carrier recombination is subsequently low, and seems not to be appropriate for light-emitting applications. In this work, the numerical simulations of electroluminescence (EL) from the GaSb/GaAs QD light-emitting diode (LED) are performed. The LED structure contains a single layer of the GaSb QDs which is inserted in a GaAs matrix, and employed as the active region of the LED. Electrical properties of the LED are presented by current density-voltage characteristics. Under forward-biased condition, simulation results indicate that the radiative recombination rate is high around the GaSb/GaAs interface and becomes gradually lower in the middle of each QD owing to the type-II band alignment. Interestingly, the radiative recombination can be enhanced and extend more into the QDs as the forward-biased voltage increases, enabling the possibility to realize light-emitting devices from type-II nanostructures. These observations can be explained by band diagrams. Furthermore, the blueshift in the EL peak energy with increasing the injected current density is found and almost proportional to the third root of the injected current density, confirming that the EL emissions are derived from the QDs.