The surface and domain structure of NbTe2

Scanning tunneling microscopy of freshly cleaved NbTe2 van der Waals surfaces reveals that Te vacancies regularly appear in the topmost chains of the Te surface layer. As a result of reduced symmetry with regard to the parent Cdl(2) structure microdomains of three possible orientational variants are formed, separated by ortho (60)- or meta (120degrees)boundaries, while the para (180degrees)-boundaries are not detected. Regions close to the boundaries are often modulated with periodicities of the adjacent domains, confirming that the boundaries in neighboring Te Nb-Te triple layers do not necessarily coincide. (C) 2002 Elsevier Science B.V. All rights reserved.