Selective epitaxy shapes a semiconductor with exceptional transport properties at the nanoscale

Mercury Telluride (HgTe) is a semiconductor with exceptional electron transport properties. For instance, a strained HgTe quantum well surrounded by Cd(Zn)Te barriers is a 2D topological insulator, a material with edge conduction channels protected against disorder and impurities. The fabrication of nano-device based on this material is thus particularly appealing for quantum electronics and spintronic applications. However, due to its strong sensitivity to electron beam exposure, achieving HgTe nanostructures is particularly challenging. Thanks to a collaboration within the ANR Inspiring project, LETI, IEMN and NEEL have demonstrated the possibility to grow in-plane HgTe nanowires by selective area molecular beam epitaxy through a nanoscale silicon oxide mask designed on a CdTe substrate. The impact of the in-plane orientation of the nanowires on their intrinsic transport properties has been studied using a multi-probe Scanning Tunneling Microscope.