Published online by Cambridge University Press: 10 February 2011
In the present work we study the effect of vertical alignment in the quantum dot array formed by successive deposition of several rows of InAlAs and InGaAs quantum dots separated by thin AIGaAs spacer layers. Transmission electron microscopy and photoluminescence studies revealed that the InAlAs QDs characterized by high areal density force InGaAs to be transformed into the denser array as compared to the case of spontaneous transformation. Using denser array of composite quantum dots in the active region of a diode laser leads to the increase in modal gain, decrease in internal loss, and decrease in the threshold current density for short cavity diodes. Room temperature continuous wave output power as high as 3.3 W at 0.87 µm is achieved.