Influence of buffer-layer construction and substrate orientation on the electron mobilities in metamorphic In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As structures on GaAs substrates

Abstract

The influence of construction of the buffer layer and misorientation of the substrate on the electrical properties of In0.70Al0.30As/In0.76Ga0.24As/In0.70Al0.30As quantum wells on a GaAs substrate is studied. The temperature dependences (in the temperature range of 4.2 K < T < 300 K) and field dependences (in magnetic fields as high as 6 T) of the sample resistances are measured. Anisotropy of the resistances in different crystallographic directions is detected; this anisotropy depends on the substrate orientation and construction of the metamorphic buffer layer. In addition, the Hall effect and the Shubnikov–de Haas effect are studied. The Shubnikov–de Haas effect is used to determine the mobilities of electrons separately in several occupied dimensionally quantized subbands in different crystallographic directions. The calculated anisotropy of mobilities is in agreement with experimental data on the anisotropy of the resistances.