STM images and scanning tunneling spectra for types A and B islands. (a) High-resolution STM image (10 × 10 nm2; Vs = 2.0 V; I = 0.25 nA) of the surface of type A islands. A rhombic unit cell showing the (2 × 2) reconstruction is outlined. (b) High-resolution STM image (10 × 10 nm2; Vs = 2.0 V; I = 0.15 nA) of the surface of type B islands. A parallelogram unit cell showing the c (4 × 8) reconstruction is outlined. (c,d) Scanning tunneling spectra measured on types A and B islands, respectively, showing semiconducting characteristics with a band gap of approximately 0.85 to 0.9 eV.
Zou et al. Nanoscale Research Letters 2013 8:510 doi:10.1186/1556-276X-8-510