MBE growth of metamorphic In(Ga)AlAs buffers

Metamorphic buffer layers were grown by MBE on GaAs-substrates using linearly graded InAlAs and InGaAlAs buffers to accommodate lattice misfit. The surface morphology was investigated by AFM, the relaxation behavior of the metamorphic buffers are studied by high resolution X-ray diffraction. The degree of relaxation is 86% for the ternary buffer and 90% for the quarternary buffer. Increasing the final In-composition of the buffer up to a value of 0.63, the In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As layers on top of the metamorphic buffer are unstrained. Transport properties of 2DEG-structures approach those of lattice matched reference samples on InP-substrates.