Metal-oxide-semiconductor devices with molecular beam epitaxy-grown Y 2O 3 on Ge

Abstract

Excellent electrical performance has been achieved on Ge metal-oxide-semiconductor (MOS) devices using molecular beam epitaxy (MBE)-deposited dielectrics of Al 2O 3/Y 2O 3 directly on Ge(1 0 0) without utilizing any interfacial layers, such as GeO x N y or Si. Slight Ge diffusion into Y 2O 3 was observed using in-situ X-ray photoelectron spectroscopy. The interface between Y 2O 3 and Ge is atomically smooth after a high-temperature anneal at 500 °C for 10 min as characterized using high-resolution transmission electron microscopy. A high κ value of Y 2O 3 of ∼17.3 and a low gate leakage current density of 7.6×10 −9 A/cm 2 have been obtained from the MOS capacitors with a total capacitance equivalent thickness (CET) of 2.41 nm. Furthermore, ring-type p-channel MOS field-effect transistors with the same gate oxides have exhibited a high drain current density of 98 mA/mm, a peak transconductance of 43 mS/mm, and a hole mobility of 241 cm 2/V s with a gate length and a gate width of 4 and 400 μm, respectively.