Photoluminescence and lasing characteristics of InGaAs/InGaAsP/InP quantum dots

The InGaAs quantum dots (QDs) were grown with InGaAsP (lambda(g)=1.0-1.1 mum) barrier, and the emission wavelength was controlled by the composition of InGaAs QD material in the range between 1.35 and 1.65 mum. It is observed that the lateral size increases and the height of the QDs decreases with the increase in relative concentration of trimethylgallium to trimethylindium supplied during InGaAs QD growth. It is seen that the higher concentration of group III alkyl supply per unit time leads to higher QD areal density, indicating that the higher concentration causes more QDs to nucleate. By optimizing the growth conditions, the QDs emitting at around 1.55 mum were grown with an areal density as high as 8x10(10) cm(-2). The lasing action between the first excited subband states at the wavelength of 1.488 mum has been observed from the ridge waveguide lasers with five QD stacks up to 260 K. The threshold current density of 3.3 kA/cm(2) at 200 K and a characteristic temperature of 118 K were measured. (C) 2004 American Institute of Physics.