Enhanced performance of InAs/GaAs quantum dot superluminescent diodes by direct Si-doping

It is necessary to improve the output power and spectral width of superluminescent diodes (SLDs) simultaneously. In this paper, we show that both the output power and the spectral width of the SLDs based on InAs/GaAs quantum dots (QDs) can be significantly enhanced by direct Si-doping in the QDs. The maximum output power of the Si-doped QD-SLD reaches 20.5 mW at an injection current of 570 mA, while that of the undoped one with an identical structure is only 17.8 mW at the injection current of 550 mA. Moreover, the broadest spectral width of the doped QD-SLD is 105 nm, while that of the undoped QD-SLD is 93 nm. The enhanced performance of the doped QD-SLDs can be attributed to the direct Si doping that leads to inactivating the nonradiative recombination centers within or near the QDs and provides excess carriers to occupy the higher excited states.