La2O3and Y2O3are used as gate dielectric in Ge MOS capacitors, and their electrical and interfacial properties are comparatively studied. Due to the much higher reactivity of La2O3with Ge than Y2O3, thicker germanate interlayer is formed, leading to better interface quality for the former. Moreover, it is found that N incorporation in the oxides reduces the formation of both germanate and GeOx, with much more obvious effect for La2O3and thus the best interface quality (a low interface-state density of 4.96 × 1011cm-2eV-1), which gives promising electrical properties: large equivalent dielectric constant (18.8), small flat-band shift (0.37 V), low gate leakage current (2.89 × 10-4A/cm2at Vg= Vfb+ 1 V), and high reliability under electrical stress.
- Ge MOS
- interface quality
- nitrogen incorporation
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering