Lanthanum germanate as dielectric for scaled Germanium metal–oxide–semiconductor devices

• Published in: Microelectronic engineering Vol. 86; no. 7; pp. 1635 - 1637
• Main Authors: Andersson, C., Rossel, C., Sousa, M., Webb, D.J., Marchiori, C., Caimi, D., Siegwart, H., Panayiotatos, Y., Dimoulas, A., Fompeyrine, J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-07-2009; Elsevier
• Subjects: Applied sciences; Compound structure devices; Electronics; Exact sciences and technology; Germanium; Passivation; Rare earth oxides; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Germanium; Rare earth oxides; Passivation; Interfacial layer; Annealing; Flat band voltage; MOS structure; Voltage capacity curve
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2009.03.096

We report a study of La
2O
3 with lanthanum germanate (LGO) as interfacial layer, or LGO alone as a gate dielectric candidate for scaled germanium metal–oxide–semiconductor devices. Capacitance–voltage (
C–V) analysis of as-deposited samples of various oxide thicknesses show a La
2O
3 with
k value of ∼24–27 with an interfacial LGO with
k value of ∼12. Upon O
2 annealing, the oxides fully transform into LGO without an interfacial layer. The paper also discusses flatband voltage (
V
fb) shifts with oxide thickness, from which positive fixed charges in La
2O
3 can be deduced. It is also shown that these charges are strongly reduced upon the O
2 anneal and LGO formation.