Molecular-beam epitaxial growth of III–V semiconductors on Ge∕Si for metal-oxide-semiconductor device fabrication

We describe the fabrication of III–V metal-oxide-semiconductor (MOS) devices on Ge∕Si virtual substrates using molecular-beam epitaxy. Migration-enhanced epitaxy and low temperature normal GaAs growth produced a sufficiently smooth surface to deposit gate oxides. A 300nm thick GaAs buffer layer was grown, followed by a 10nm growth of In0.2Ga0.8As high mobility channel layer. An 8.5nm thick Al2O3 layer was deposited ex situ by atomic-layer deposition. Capacitance-voltage (C-V) characteristics show the unpinning of Fermi level. This work suggests this materials combination as a promising candidate for the design of advanced, nonclassical complementary MOS and optoelectronic devices on Si substrates.