Thin germanium-carbon alloy layers grown directly on silicon for metal-oxide-semiconductor device applications

We report the growth and characterization of thin (<35 nm) germanium-carbon alloy (Ge1-x Cx) layers grown directly on Si by ultrahigh-vacuum chemical vapor deposition, with capacitance-voltage and leakage characteristics of the first high- κ /metal gate metal-oxide- semiconductor (MOS) capacitors fabricated on Ge1-x Cx. The Ge1-x Cx layers have an average C concentration of approximately 1 at. % and were obtained using the reaction of C H3 Ge H3 and Ge H4 at a deposition pressure of 5 mTorr and growth temperature of 450 °C. The Ge1-x Cx films were characterized by secondary ion mass spectrometry, atomic force microscopy, x-ray diffraction, and cross-sectional transmission electron microscopy. A modified etch pit technique was used to calculate the threading dislocation density. The x-ray diffraction results showed that the Ge1-x Cx layers were partially relaxed. The fabricated MOS capacitors exhibited well-behaved electrical characteristics, demonstrating the feasibility of Ge1-x Cx layers on Si for future high-carrier-mobility MOS devices.