Recently, a research team led by Prof. ZHAO Jianhua, at the State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, demonstrated their collaborative work on the successful growth of near full-composition-range high-quality GaAs_1-xSb_x nanowires by molecular-beam epitaxy (MBE). 

GaAs_1-xSb_x has a large bandgap from 870 nm (GaAs) to 1720 nm (GaSb) at room temperature. It thus can be used in optical fiber communication systems, infrared light-emitting diodes, photodetectors, lasers, heterojunction bipolar transistors, etc.

While, the fabrication of high-quality GaAs_1-xSb_x films with high Sb content is difficult, due to a large lattice mismatch between the GaAs_1-xSb_x films and III-V semiconductor substrates.

Recently, some groups reported the growth of low-Sb-content GaAs_1-xSb_x nanowires (x < 0.5) on Si substrates employing metal-organic chemical vapor deposition and MBE techniques.

Through tuning the Sb and As fluxes, and the As background, Prof. ZHAO and her team, for the first time, have fabricated full-composition-range GaAs_1-xSb_x nanowires on Si substrate and GaAs stems using MBE. Transmission electron microscopy results confirm that the GaAs1-xSbx nanowires have pure zinc-blende crystal structure.

They collaborated with Prof. SUN Baoquan and Prof. TAN Pingheng at Institute of Semiconductors, and Prof. PAN Anlian at Hunan University to investigate the optical property of GaAs_1-xSb_x nanowires.  

The photoluminescence spectra confirm that the emission wavelength of the GaAs_1-xSb_x nanowires can be tuned from 844 nm (GaAs) to 1760 nm (GaAs_0.07Sb_0.93) at 77 K. The bandgap of the GaAs_1-xSb_x nanowires is tuned by 0.76 eV. Room-temperature Raman spectra confirm that optical phonons of the GaAs_1-xSb_x nanowires show red-shift with x increasing.  

Field-effect transistors based on individual GaAs_1-xSb_x nanowires show rectifying behavior in low Sb content devices, and but not in devices with high Sb content. The broad tunability of this antimony-based ternary alloy opens up new band-engineering opportunities for next-generation near-IR light emitting diodes, lasers, optical fiber communication, etc. 

This work entitled with Near Full-Composition-Range High-Quality GaAs_1-xSb_xNanowires Grown by Molecular-Beam Epitaxy was published online in Nano Letters.  

This work was supported by the MOST of China and NSF of China. 

SEM and TEM images of near full-composition-range GaAs_1-xSb_x nanowires, and the PL spectra of GaAs_1-xSb_x nanowires at 77 K. (Image by Prof. ZHAO Jianhua et al.)