Ftir And Afm Studies Of The Ge On Porous Silicon/si Substrate Hetero-structure Obtained By Molecular Beam Epitaxy

The single crystal Ge layers have been deposited by molecular beam epitaxy on porous silicon (PSi) substrate, with different thicknesses (40 nm and 80 nm) at the growth temperature of 500°C and 600°C. During deposition, the pore network of PSi layers has been filled with Ge. Fourier transformed infrared spectroscopy (FTIR) and Atomic force microscopy (AFM) have been applied for investigation of vibrational modes and morphological properties of the Ge on PSi layers. AFM investigation showed the surface roughness and pyramid like hillocks. It also confirmed the nanometric size of the crystallites. FTIR absorption measurements showed different vibrational modes present in the Si1-xGex structures. The observed vibrational frequencies depend strongly on the growth temperature.