Controllable growth and unexpected effects of Ge nanocrystals

Semiconductor nanostructured Ge is a unique material of widespread technological applications, particularly in the field of microelectronics. New strategies for controllable growth and an understanding of the effects of Ge nanocrystals inducted by Au nanoparticles in Au/Ge bilayer films are of fundamental importance in the development of micro/nanodevices. After an extensive search in the published literature, it is found that the previous nanostructures are one-dimensional nanomaterials such as nanowires, nanorods, nanobelts/nanoribbons, and nanotubes, two-dimensional nanoscale thin films, or zero-dimensional nanoparticles, which all have integer dimensions. Herein, the noninteger dimensional Ge nanostructures, which are called nanofractals, were successfully assembled by high-vacuum thermal evaporation techniques. A widely applicable annealing route to produce Ge nanocrystals in the form of nanoparticles, nanorings, and nanofractals is presented in detail. To our surprise, we found that a Au/Ge bilayer film with an interesting nanofractal showed a nonlinear voltage-current behavior. This result suggested that the Au/Ge bilayer film may be a promising material to facilitate future design improvement of micro/nanodevices for microelectronic applications. © 2011 American Chemical Society.