27-10-2012, 12:13 PM
High Mobility SiGe/Si Transistor Structures on Sapphire Substrates using Ion Implantation
ABSTRACT
We report the fabrication of high mobility n-type SiGe/Si transistor structures on sapphire substrates by ion implanting
phosphorus ions into strained 10-nm-thick silicon channels. The strained Si channels were sandwiched between Si(sub
0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer
layers. After the molecular beam epitaxy film growth process was completed, donors were introduced and activated using ion
implantation and postannealing processes. Microstructural characterization of the buffer layer, virtual substrate, and electron
conduction structure using high resolution x-ray diffraction, cross-sectional transmission electron microscopy, atomic force
microscopy, and secondary ion mass spectroscopy are reported. Room temperature electron mobilities up to 900 sq cm/V s
at a carrier density of 1.3 x 10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that
determines mobility. with the highest mobility observed for electron densities in the 1-2 x 10(exp 12)/sq cm range.
ABSTRACT
We report the fabrication of high mobility n-type SiGe/Si transistor structures on sapphire substrates by ion implanting
phosphorus ions into strained 10-nm-thick silicon channels. The strained Si channels were sandwiched between Si(sub
0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer
layers. After the molecular beam epitaxy film growth process was completed, donors were introduced and activated using ion
implantation and postannealing processes. Microstructural characterization of the buffer layer, virtual substrate, and electron
conduction structure using high resolution x-ray diffraction, cross-sectional transmission electron microscopy, atomic force
microscopy, and secondary ion mass spectroscopy are reported. Room temperature electron mobilities up to 900 sq cm/V s
at a carrier density of 1.3 x 10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that
determines mobility. with the highest mobility observed for electron densities in the 1-2 x 10(exp 12)/sq cm range.