Abstract: A smooth germanium layer which can be grown directly on a silicon semiconductor substrate by exposing the substrate to germanium precursor in the presence of phosphine at temperature of about 350 C. The germanium layer formation can be achieved with or without a SiGe seed layer. The process to form the germanium layer can be integrated into standard CMOS processing to efficiently form a structure embodying a thin, highly strained germanium layer. Such structure can enable processing flexibility. The germanium layer can also provide unique physical properties such as in an opto-electronic devices, or to enable formation of a layer of group III-V material on a silicon substrate.