Semiconductor nanowires are attractive materials for devices ranging from single photon sources to biosensors and vertical transistors. These tiny crystalline semiconducting needles could help to extend transistor downscaling due to the advantageous electrostatic coupling offered by the gate geometry. Another benefit is that their very small lateral dimensions (<50 nm) allow for efficient elastic strain relaxation when they are combined on different substrate materials.

Nanowire stem extends growth window

Now researchers at Lund University have taken the technology one step further with the introduction of a new nanowire material and its integration. The team studied nanowires made of InSb, which have been very seldom reported previously, and integrated them on standard substrates made of InAs, InP and GaAs using a metalorganic vapour phase epitaxy (MOVPE) reactor. InSb has the highest bulk electron mobility of 77,000 cm2 V–1s–1. A key result is that using a short stem of substrate material drastically improves the possibility to grow these nanowires under a wide range of conditions, where they do not normally grow. The nanowire template technology provides a larger temperature range, leading for instance to defect-free perfect InSb nanowires. A controlled array of these nanowires is shown in the figure above.

On a fundamental level, the extreme lattice mismatches investigated in this study (up to 14.6% mismatch for InSb/GaAs) should also favour new theoretical developments on elastic strain relaxation in axial nanowire heterostructures. Future work will include detailed experimental strain evaluations at the interfaces and realization of vertical devices.

The researchers presented their work in Nanotechnology.