Metamorphic InAlAs/InGaAs/InAlAs/GaAs HEMT heterostructures containing strained superlattices and inverse steps in the metamorphic buffer

Metamorphic InхAl1−хAs buffer design features influence on electrophysical and structural properties of the heterostructures was investigated. Two types of MHEMT heterostructures In0.70Al0.30As/In0.76Ga0.24As with novel design contained inverse steps or strained superlattices were grown by MBE on GaAs substrates. Electrophysical properties of the heterostructures were characterized by Hall measurements, while the structural features were described with the help of different transmission electron microscopy techniques. The metamorphic HEMT with strained superlattices inserted in the metamorphic buffer had the smoother surface and more defect-free crystal structure, as well as a higher Hall mobility, than metamorphic HEMT with inverse steps within the metamorphic buffer.

► Two new designs of metamorphic buffer (MB) for HEMT InGaAs/InAlAs on GaAs substrates. ► The comparison of heterostructures with different designs of MB. ► Higher electron mobility and smoother surface for heterostructure with strained superlattices in MB. ► Lower electron mobility and rougher surface for heterostructure with inverse steps in MB. ► The effect of threading dislocation blocking in MB with strained superlattices.