Articles you may be interested inCombined molecular beam epitaxy low temperature scanning tunneling microscopy system: Enabling atomic scale characterization of semiconductor surfaces and interfaces Role of surface steps in the arrangement of silicon nano-dots on a vicinal Si(111) surface: Scanning tunneling microscopy investigation Origin, symmetry, and temperature dependence of the perturbation induced by Si extrinsic defects on the Sn/Si(111) α surface: A scanning tunneling microscopy studyThe scanning tunneling microscope has been employed to study the morphology, atomic surface structures, and grain interface of hydrogenated nanocrystalline silicon ͑nc-Si:H͒ before and after hydrofluoric acid ͑HF͒ etching. It was found: ͑1͒ The nc-Si:H films were composed of many different sizes of grains and these grains were composed of many finer grains. ͑2͒ There were line structures on the surface of the fine grains and loop structures at the grain boundaries without HF treatment. After etching, two more structures were observed: loop structures on the surface of fine grains and spider bonding structures besides the interface of fine grains. ͑3͒ The loop structures found at the grain boundaries was larger and more irregular than those on the grain surfaces. Line structures were similar to crystal silicon, but the distance between lines was enlarged. Considering the experimental results, a discussion was made about the formation mechanism of these atomic structures.

The stability of nanometer-or atomic-scale structures will affect the quality of nanometer-scale devices significantly. In these experiments, an ultrahigh vacuum scanning tunneling microscope was used to fabricate nanometer or atomic structures and to observe the stability of these structures.

Scanning tunneling microscopy (STM) was used to characterize the surface topography of polyacrylonitrile (PAN)-based carbon fibers before and after electrochemical treatment, stretch resistance test, and high-temperature treatment.A new kind of spiral structures was found, which was not only on the surface but also in the inner layer. The spiral structure of the fibers was caused by the spinning process. The fiber structure contained the shape of the precursor. There were some large cracks in the carbon fibers after the stretching resistance test. The large cracks can result in carbon fiber breaking under certain stress conditions. The difference in the structures of the carbon fibers before and after the high-temperature treatment was determined.