Effect of InGaAs capping layer on the properties of InAs/InGaAs quantum dots and lasers.

We report the effects of In[SUB0.33]Ga[SUB0.67]As capping layers on the structural and optical properties of InAs self-organized quantum dots grown by gas-source molecular-beam epitaxy. With different deposition methods for the InGaAs capping layer, the quantum-dot density can be adjusted from 2.3 × 10[SUP10] to 1.7 × 10[SUP11]cm[SUP-2]. As-cleaved 3.98-mm-long diode laser using triple stacks of InAs quantum dots with the capping layer grown by GaAs/InAs sequential binary growth demonstrates an emission wavelength of 1305 nm and a threshold current density of 360 A/cm[SUP2]. A ground-state saturation gain of 16.6 cm[SUP-1] is achieved due to the high dot density. [ABSTRACT FROM AUTHOR]