Surface and interface modification of alternative semiconductor materials for advanced transistors
Alternative semiconductor materials have the potential to replace silicon in next generation transistors. However, the lack of a stable insulating oxide such as SiO2 with high quality electrical properties prevents the further fabrication of competitive metal oxide semiconductor field effect transistors (MOSFETs). Germanium and gallium arsenide, two widely investigated semiconductor materials, have high prospects for generating high quality surfaces and interfaces between the dielectric layer
... d the semiconductor. In this thesis, wet chemistry cleaning methods have successfully removed the native oxide and other impurities on the Ge and GaAs surface. With further sulfur passivation in (NH4)2S solution, a clean passivated Ge and GaAs surface can be formed which shows appropriate stability and reliability for fabrication. Physical and chemical characterization has been performed on multilayer film structures after the high-κ dielectric films are grown by atomic layer deposition. Electric properties of the MOSFET confirm that the sulfur passivation has greatly decreased the interface state density. The convenience and low cost of wet chemistry cleaning and passivation provide a reliable strategy for the application of alternative semiconductor materials like Ge and GaAs in future transistors and related devices.