Effects of buffer layers on the structural and electronic properties of InSbInSb films

Abstract

We have investigated the effects of various buffer layers on the structural and electronic properties of nn-doped InSbInSb films. We find a significant decrease in room-temperature electron mobility of InSbInSb films grown on low-misfit GaSbGaSb buffers, and a significant increase in room-temperature electron mobility of InSbInSb films grown on high-misfit InAlSbInAlSb or step-graded GaSb+InAlSbGaSb+InAlSb buffers, in comparison with those grown directly on GaAsGaAs. Plan-view transmission electron microscopy (TEM) indicates a significant increase in threading dislocation density for InSbInSb films grown on the low-misfit buffers, and a significant decrease in threading dislocation density for InSbInSb films grown on high-misfit or step-graded buffers, in comparison with those grown directly on GaAsGaAs. Cross-sectional TEM reveals the role of the film/buffer interfaces in the nucleation (filtering) of threading dislocations for the low-misfit (high-misfit and step-graded) buffers. A quantitative analysis of electron mobility and carrier-concentration dependence on threading dislocation density suggests that electron scattering from the lattice dilation associated with threading dislocations has a stronger effect on electron mobility than electron scattering from the depletion potential surrounding the dislocations. Furthermore, while lattice dilation is the predominant mobility-limiting factor in these nn-doped InSbInSb films, ionized impurity scattering associated with dopants also plays a role in limiting the electron mobility.