Exploiting flux shadowing for strain and bending engineering in core-shell nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Gallium Arsenide (GaAs) nanowires (NWs) are crucial for advanced electronic and optoelectronic devices.
• Controlling material composition and strain in NWs is essential for tailoring their properties.

Purpose of the Study:

• To investigate the non-uniform shell growth of Indium Gallium Arsenide (InGaAs) on GaAs NWs.
• To understand and control the strain distribution and bending profile of NWs based on substrate patterning.
• To establish a method for designing NW-based devices with length-selective strain.

Main Methods:

• Utilized molecular beam epitaxy (MBE) for InGaAs shell growth on GaAs NW cores.
• Employed pre-patterned silicon substrates with varying pitch sizes (0.1 μm to 10 μm).
• Analyzed the influence of substrate layout and MBE cell geometry on NW growth and strain.

Main Results:

• Achieved non-uniform InGaAs shell growth on GaAs NWs, resulting in modified strain distributions.
• Observed that NW arrays with high density exhibit bending profiles with distinct straight (low strain) and bent (high strain) segments.
• Demonstrated that the lengths of these straight and bent segments are controllable by adjusting the substrate pitch size.

Conclusions:

• Precise control over InGaAs shell growth enables tailored strain distribution along GaAs NWs.
• The ability to control segment lengths offers a pathway for designing novel NW devices with specific strain engineering.
• This technique is vital for advancing the performance and functionality of semiconductor nanowire-based technologies.