Antimony variations in GaAs/GaAsSb heterostructured nanowires (Vol. 44 No. 6)

Schematic band diagram of a zinc blende GaAsSb insert in a wurtzite GaAs nanowire. The model is based on the structural and compositional analysis by scanning transmission electron microscopy and optical characterization by micro-photoluminescence.

Semiconductor nanowires have attracted huge attention recently due to their unique and often superior properties compared to bulk or planar counterparts. Complex heterostructures can be made and several nanowire-based devices (e.g. solar cells) have been realized. GaAsSb is an interesting ternary compound semiconductor because of its tunable bandgap and the possibility for both type I and type II band alignment with GaAs. In the present study 20-80 nm long zinc blende GaAsSb segments in wurtzite GaAs bare-core and GaAs/AlGaAs core-shell nanowires were studied. The work established the presence of both axial and radial compositional variations in the GaAsSb segments and their effect on the optical properties of these nanowires. The Sb concentration profiles within the inserts were determined using energy dispersive X-ray spectroscopy and quantitative scanning transmission electron microscopy and related directly to micro-photoluminescence measurements for the same single nanowires. The results of the article are relevant for further growth optimization and tailoring of the optical properties of GaAs/GaAsSb heterostructured nanowires.

J. Todorovic, H. Kauko, L. Ahtapodov, A. F. Moses, P. Olk, D. L. Dheeraj, B. O. Fimland, H. Weman and A. T. J. van Helvoort, ‘The effects of Sb concentration variation on the optical properties of GaAsSb/GaAs heterostructured nanowires’, Semicond. Sci. Technol. 28, 115004 (2013)