Critical layer thickness of In0.80Ga0.20As/In0.52Al0.48As heterostructures

The critical layer thickness of n-In 0.52 Al 0.48 As/strained-In 0.8 Ga 0.2 As/In 0.52 Al 0.48 As grown on InP substrates was investigated by measuring the photoluminescence spectra. These pseudomorphic heterostructures grown by molecular beam epitaxy attained the highest mobility, 16,200 cm 2 /V·s, at room temperature. The photoluminescence emission intensity decreased in the thickness range of 20 to 25 nm for the In 0.8 Ga 0.2 As layer. These results indicate that the critical layer thickness of this structure follows the energy balance model rather than the mechanical equilibrium model. In addition, this critical value is in good agreement with the results based on the electron mobility behavior.