High-efficiency light-emitting diodes at /spl ap/1.3 /spl mu/m using InAs-InGaAs quantum dots

Light-emitting diodes (LEDs) based on long-wavelength, self-assembled InAs-InGaAs quantum dots (QDs) are demonstrated and characterized. The LEDs consist of a single layer of QDs positioned at /spl lambda//2 from a top gold mirror to enhance the extraction efficiency. The external quantum efficiency at room temperature is 1%, which corresponds to an estimated 13% radiative efficiency. High-injection electroluminescence and photovoltage spectra under reverse bias allow us to determine the transition energies of excited states in the QDs and bidimensional states in the adjacent InGaAs quantum well.