Rare earth oxides as high-k dielectrics for Ge based MOS devices: An electrical study of Pt/Gd2O3/Ge capacitors

• Published in: Solid-state electronics 2007-01, Vol.51 (1), p.164-169
• Main Authors: Evangelou, E.K., Mavrou, G., Dimoulas, A., Konofaos, N.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bulk states; Compound structure devices; Dielectric, amorphous and glass solid devices; Electrical properties; Electronics; Exact sciences and technology; Germanium; Interface states; MBE; Microelectronic fabrication (materials and surfaces technology); Rare earth oxides; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Transistors
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2006.10.011

Germanium technology aiming at the fabrication of functional devices strongly depends on the electrical behaviour of both the oxide bulk and the oxide/Ge interface. Field effect transistors underperform and express non ideal characteristics due to high values of interface defects in conjunction with bulk states. In this paper, we show that rare earth oxide layers of Gd2O3 prepared by molecular beam deposition on Ge substrates produce improved insulating characteristics. The current density at 1V was as low as J=50nA/cm2. The calculated value of the dielectric constant was around 10 and an EOT value equal to 3.7nm was obtained, while the density of the interface states was approximately 2×1012cm−2eV−1. A detailed analysis of the electrical measurements of MOS capacitors revealed the existence of bulk electron traps in the semiconductor which need special attention if rare earth oxides are to be used in Ge based MOS devices.