Researchers at C2N and the National University of Singapore have demonstrated a new way to control the crystal structure of semiconductor nanowires using an electric field, paving the way for the on-demand fabrication of crystal-phase quantum dots.
Controlling different crystal phases within nanowires presents both a challenge and an opportunity. While unwanted phase mixing can degrade device quality, deliberately controlling these phases can be used to create new quantum structures known as crystal-phase quantum dots (CPQDs).
In a study published in ACS Nano, the team shows that applying an electric field during the vapour–liquid–solid growth of GaAs nanowires enables precise switching between two crystal structures—zinc blende (ZB) and wurtzite (WZ). This switching occurs with monolayer precision, making it possible to fabricate CPQDs with unprecedented control.
This breakthrough was made possible by custom micro-engineered silicon platforms operated inside the in-situ transmission electron microscope, NanoMAX. Nanowires were grown by chemical vapor deposition while their formation was monitored in real time. The applied E-field triggers an immediate switch between the zinc blende and wurtzite phases, generating atomically sharp interfaces. These experimental findings are supported by numerical simulations, which reveal how the electric field modifies the shape of the catalyst droplet at the nanowire tip, ultimately dictating the crystal phase that forms.
Together, these results mark a major advance toward the controlled fabrication of CPQDs, opening new possibilities for quantum light sources and nanoscale quantum technologies.
Références
Electric-field-assisted phase switching for crystal phase quantum dot fabrication in GaAs nanowires.
Qiang Yu,1 Khakimjon Saidov,2 Ivan Erofeev,2 Khalil Hassebi,1 Chen Wei,1 Charles Renard,1 Laetitia Vincent,1 Frank Glas,1 Utkur Mirsaidov,2* Federico Panciera1*
ACS Nano, DOI: https://doi.org/10.1021/acsnano.5c15434
Affiliations
1 Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
2 Centre for BioImaging Sciences, Department of Biological Sciences and Physics, National University of Singapore, Singapore 117557
Contact : Federico PANCIERA
Key words : semiconductor nanowires, in situ TEM, crystal growth, polytypism, electric field, crystal phase quantum dots, vapor-liquid-solid
Figure 1: Crystal phase changes induced by an E-field. (left) Schematic view of the experimental setup showing that applying an E-field during growth induces the crystal phase switching in GaAs nanowires. The E-field dynamically deforms the catalyst droplet, modulating its contact angle beyond a critical threshold to trigger zinc blende (ZB)–wurtzite (WZ) transitions with monolayer precision. (right) Example of crystal phase quantum dots fabricated by the E-field method. The scale bar is 5 nm.
