Evidence of Trigonal Dangling Bonds at the Ge(111)/Oxide Interface by Electrically Detected Magnetic Resonance

Abstract

Despite a renewed interest in Ge as a competitor with Si for a broad range of electronic applications, the microstructure and the electronic properties of the dangling bonds that, in analogy with Si, are expected at the Ge/oxide interface have escaped a firm spectroscopy observation and characterization. Clear evidence based on contactless electrically detected magnetic resonance spectroscopy of a dangling bond at the Geð111Þ=GeO 2 interface is reported in this Letter. This result supports the similarity between dangling bonds at the Si(111)/oxide and Ge(111)/oxide interfaces, both showing C 3v trigonal point symmetry with the main axis oriented along the h111i direction. In contrast, at the Ge(001)/oxide interface the absence of the trigonal center in favor of a lower symmetry dangling bond marks the difference with the Si(001)/ oxide interface, where both centers are present and the one having higher point symmetry prevails. This fact is rationalized in terms of suboxide interface rearrangement and oxide viscoelasticity, which promote the generation of the nonaxial centers at distorted dimers. The unambiguous identification of the centers at the Ge/oxide interfaces yields a deeper insight into the physical properties of the suboxide interface structure and offers a valid indicator for the evaluation of different surface capping and passivation techniques, with the potential to boost the Ge-related technology.

High-K materials and metal gates for CMOS applications

“…Thus, the Ge DB does exist in the gap. The Ge DB signal has finally been observed at a defective Ge:GeO 2 interfaces by Paleari [352] using electrically detected magnetic resonance, Fig 81. It shows the angular response expected for a P b center. Recently, the reaction of hydrogen with the Ge P b center has been observed by Stesmans [353].…”

Carrier density modulation in a germanium heterostructure by ferroelectric switching

“…There has recently been renewed interest in using Ge as a channel material [14][15][16][17] . As germanium is not as readily oxidized as silicon, one stands a much better chance of growing a ferroelectric oxide on Ge without any interfacial layer.…”

Orientation-dependent structural and electronic properties of Ge/a-GeO2 interfaces: first-principles study

“…When a Ge DB is in an oxygen-rich region and has more positively charged state, the DB level may shift closer to the conduction band. This could explain the exper imental observation that • Ge ≡ Ge 3 defects (called 'P b centers' in the previous studies [30]) are more difficult to passivate with H [7], because both DBs and H tend to be negatively charged. Overall, the electronic structures of the Ge/ GeO 2 interface are dominated by the charge neutrality level of the Ge defect atoms.…”