p-doped 1.3 μm InAs/GaAs quantum-dot laser with a low threshold current density and high differential efficiency

A modification of the thickness of the low-growth-temperature component of the GaAs spacer layers in multilayer 1.3 mu m InAs/GaAs quantum-dot (QD) lasers has been used to significantly improve device performance. For a p-doped seven-layer device, a reduction in the thickness of this component from 15 to 2 nm results in a reduced reverse bias leakage current and an increase in the intensity of the spontaneous emission. In addition, a significant reduction of the threshold current density and an increase of the external differential efficiency at room temperature are obtained. These improvements indicate a reduced defect density, most probably a combination of the selective elimination of a very low density of dislocated dots and a smaller number of defects in the thinner low-growth-temperature component of the GaAs spacer layer. (c) 2006 American Institute of Physics.