Optimal growth conditions for strained GaAs/InxAl1−xAs core–shell nanowires with enhanced electronic properties

Abstract

In material systems such as GaAs core/InxAl1−xAs shell nanowires, the elastic strain and the resulting electronic properties of the core can be continuously tailored via the selection of the ternary shell composition, extending the functionality range of the core material. Typically, the nanowire axis is oriented along 1¯1¯1¯, and the epitaxial growth of the shell onto the 11¯0 sidewalls of the core is performed at quite low temperatures, following common knowledge from thin film technology. Such conditions achieve smooth surfaces, though at the potential cost of the structural quality. Here, we examine the relation between the shell growth temperature and the electronic properties of the core, as the latter are dictated by the quality of the strained core/shell interface. We demonstrate lower rates of non-radiative recombination and scattering of electrons at the interface in nanowires with higher shell growth temperatures, reaching optimal values at 500 °C. Above this temperature, the electronic quality of the interface degrades in correlation with compositional and morphological deviations that occur in the shell. These findings manifest the key role of the shell growth temperature in the optimization of the electronic properties toward the realization of functional devices with low non-radiative carrier recombination and high electron mobility.