Fig. 5: Electron microscopy images of surface oxides observed.
From: Systematic improvements in transmon qubit coherence enabled by niobium surface encapsulation
Oxides for (a) Al-capped Nb, (b) TiN-capped Nb, (c) baseline Nb, and (d) Ta-capped Nb qubits prepared on sapphire are presented. Similar images of surface oxides for (e) baseline Nb, and (f) Ta capped Nb qubits prepared on silicon are also presented. The oxides are identified with arrows and tabulated in Table 2. Scale bars represent 10 nm.
