Control Of Silicon And Germanium Nanostructures Through Hydrogen Treatments

Micro-nanofabrication is more and more important for information technology, including controlling well nanostructures in large scale integrated circuits.The sizes of devices shrink and performance continues to improve, the basic structure of the device from the plane (2D) into the three-dimensional (3D) structure, and the developments for various types of dual-gate/gate Fin-FET type and nanowire based MOSFETs have been attracted extraordinarily attention. For MOSFETs, the features on the nanostructures of silicon surface are very important for the performance of devices. It is necessary to smooth the channel surface, in order to obtain high carrier mobility. An etching technique for three-dimensional channels is unable to achieve directly a smooth surface, and thus the development of various processing methods to obtain the desired surface of the channel, including chemical polishing, thermal oxidation, polishing, and hydrogen annealing treatment.In this thesis, we focus on unstanding the interaction between hydrogen and silicon(and germanium) atoms during annealing at high temperatures, and developing the control of silicon (and germanium) nanostructures through hydrogen treatments. The evolvement of surface morphology of silicon nanostructures is investigated with various experimental conditions of hydrogen treatment, including temperature, hydrogen components and time, and behavior of the surface morphology evolved under different key parameters has been understood. Meanwhile, the evolvement characteristics of formation of silicon nanostructures under conditions of hydrogen treatment are simulated by using the Monte Carlo method, explaining the basic process of the evolution of structural morphology at high temperatures. Moreover, the surface morphologies of germanium wafers having different crystal orientations under different conditions of hydrogen treatments are investigated. The present results are very useful for developing nano-scaled MOSFET, nanowire-based solar cells, and others.