Near-infrared wavelength intersubband transitions in high indium content InGaAs/AlAs quantum wells grown on GaAs

The authors report intersubband transitions shorter than 2 mu m in square and coupled InGaAs/AlAs quantum wells (QWs) grown on GaAs substrates. The linearly graded buffer technique is used to facilitate the growth of quantum wells with indium contents of 50 and 60%. E-12 of 720meV (1.7 mu m) is achieved in six monlayer (ML) wide In0.6Ga0.4As/AlAs QWs. Asymmetrically coupled In0.5Ga0.5As/AlAs QWs exhibit intersubband transition as high as 780meV (1.59 mu m) for the 1-4 transition.