Atomic Layer Deposition and Strain Analysis of Epitaxial GaN-ZnO Core–Shell Nanowires

Abstract

We demonstrate the epitaxial coating of GaN NWs with an epitaxial ZnO shell by atomic layer deposition at 300 °C. Scanning transmission electron microscopy proves a sharp and defect-free coherent interface. The strain in the core–shell structure due to the lattice mismatch and different thermal expansion coefficients of GaN and ZnO was analyzed using 4D-STEM strain mapping and Raman spectroscopy and compared to theoretical calculations. The results highlight the outstanding advantages of epitaxial shell growth using atomic layer deposition, e.g., conformal coating and precise thickness control.

Effective surface passivation of GaAs nanowire photodetectors by a thin ZnO capping

“…23–26 Nevertheless, the potential for modifying photodetectors based on III–V NWs has still not been fully explored up to date. Although there exist some reports based on a combination of III–V NWs and ZnO, 27–30 they commonly use thick n-type ZnO shells, which are unable to extract the sole role of passivation because of the formation of a possible strong pn junction and strain defects due to lattice mismatch. The use of an ultrathin oxide passivation layer can effectively solve all these side effects brought about by a thick passivation layer, as the thin thickness is not enough to accumulate a large enough strain to change the sample morphology or band bending.…”