Structural correlation of band‐gap modifications induced in mercury telluride by dimensional constraint in single walled carbon nanotubes

A unique tubular structure for mercury telluride HgTe grown inside narrow single walled carbon nanotubes (SWNTs) is described with both Hg and Te in novel coordination geometries. Two unique projections were obtained by high resolution transmission electron microscopy from two separate encapsulated crystal fragments enabled reconstruction of a three dimensional atomic arrangement structurally consistent with both fragments. The observed structure was separately determined by quantum mechanical calculations that confirmed the global stability of the HgTe structure and demonstrated conclusively that it arises as a result of its constrained low‐dimensionality. We have also calculated that this structural change is correlated directly with a fundamentally modified electronic structure resulting in the transformation of HgTe from a bulk semimetal to a semiconductor when confined within a SWNT. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)