MBE growth and characterisation of InGaAs quantum dot lasers

High quality self-assembled InGaAs quantum dots have been formed on GaAs by molecular beam epitaxy via Stranski-Krastonov growth mode, and have been employed to produce quantum dot lasers with reasonably good properties. The effects of growth conditions, substrate misorientation, and doping in quantum dots on the characteristics of quantum dots and quantum dot lasers are presented. It has been shown that higher density of quantum dots is obtained under higher As flux because the diffusion length of Ga adatoms is reduced. Higher degree of substrate misorientation also leads to higher density of quantum dots since the kinks on the surface have similar effect on the diffusion of cations. It is also found that doping in the quantum dots plays an important role in the performance of quantum dot lasers. Room temperature continuous wave operation has been achieved on Be-doped quantum dot lasers. Under pulse operation, characteristic temperature as high as 121 K between 20 and 70°C has been obtained.