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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 Ge(111)/GeO2 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 âŸ̈111⟩ 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.

The electrical quality of the GeO2/Ge interface, prior to and after Gd2O3 deposition, has been investigated as a function of the oxidizer (atomic O, O-2, O-3) used for the GeO2 based passivation of the Ge surface. In particular, the density of interface traps depends on the details of the Ge oxidation process and on the reactivity of the GeO2 passivation layer with the overlying Gd2O3 film. Complementary compositional depth profiling analysis shows that the oxygen content in the interfacial layer varies as a function of the type of oxidizer and plays a key role in dictating the interface chemistry and the electrical features of the MOS structures. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.031206jes] All rights reserved.

We report our work on the characterization by electrically detected magnetic resonance (EDMR) measurements of silicon nanowires (SiNWs) produced by different top-down processes. SiNWs were fabricated starting from SOI wafers using standard e-beam lithography and anisotropic wet etching or by metal-assisted chemical etching. Further oxidation was used to reduce the wire cross section. Different EDMR implementations were used to address the electronic wave function of donors (P) and to characterize point defects at the SiNWs/SiO2 interface. The EDMR spectra of as produced SiNWs with high donor concentration ([P]= 10(18) cm(-3)) show a single line related to delocalized electrons. SiNWs produced on substrates with lower donor concentration ([P] < 10(16) cm(-3)) reveal the doublet related to substitutional P in Si, as well as lines related to interfacial defects such as Pb-0, Pb, E', and E'-like. The EDMR spectra of samples produced by metal-assisted chemical etching exposed to post production oxidation reveal a disordered and defective interface and the disappearance of the P related signal. Forming gas annealing, on the other hand, reduces the contribution of interfacial defects and allows a better resolution of the P related doublet

In Ge-based metal oxide semiconductor technology, the insertion of a passivation layer seems to be crucial in unpinning the Fermi level at the interface and in reducing the amount of interface defects. GeO2 was obtained by atomic oxygen (AO), molecular oxygen or ozone chemisorption. Atomic or molecular oxygen was used in the deposition of Gd2O3. Gd2O3 thin films were grown by molecular beam deposition directly on (1 0 0) Ge or on a GeO2 interlayer. The chemical nature of the Gd2O3/Ge interface was characterized by time-of-flight secondary ion mass spectrometry depth profiles. Without GeO 2 layer Gd and Ge interdiffusion is observed and the concomitant formation of GeOGd bonds is also supported by X-ray photoelectron spectroscopy energy shift at the Ge 3d peak and by a singularity in the interface defect energy distribution at ∼0.48 eV. Further, depending on the GeO2 formation process, the profile shape of Ge and O related secondary ions at the GeO2/Ge interface can be related with a defective Ge region close to the GeO2/Ge. In particular, considering the ratio between Ge and GeO2 related secondary ion signals, the interlayer passivated using AO turns out to be comparatively enriched in Ge, while the use of ozone for GeO2 formation leads to a Ge deficient layer. © 2010 Elsevier B.V. All rights reserved.

GeO2 was proposed as valuable passivation layer at the surface with Ge to integrate oxide with high dielectric constant in Ge-based logic devices. Hence, the identification of the defects present at different Ge/GeO2 interfaces becomes a mandatory issue to predict the electrical features of devices based on such materials. High sensitive electrically detected magnetic resonance measurements were performed to study the microstructure of defects occurring at such an interface. The influence of the oxidation temperature on the electrically active paramagnetic traps was investigated.

High mobility substrates and silicon nanowires are important key elements in the development of advanced devices targeting a vast range of functionalities. In almost all applications the interface between the semiconductor and the oxide layer placed on top or all around plays a crucial role in determining the device performance. The investigation of defects at these interfaces is therefore mandatory to fully exploit the advantages of these systems. We report on the application of electrically detected magnetic resonance (EDMR) techniques in the investigation of defects at the interface between Ge and GeO2 (or GeOx) and at the interface between silicon nanowires (SiNWs) and SiO2. © 2011 Elsevier B.V. All rights reserved.

The hexagonal phase of La2 O3 is obtained upon vacuum annealing of hydroxilated La2 O3 films grown with atomic layer deposition at 200 °C using La (Pi rCp)3 and O3. A dielectric constant value of 24±2 and 22±1 is obtained on Si-based and Ge-based metal-oxide-semiconductor capacitors, respectively. However, the relatively good La2 O3 dielectric properties are associated with significant interface reactivity on both semiconductor substrates. This leads to the identification of a minimum critical thickness that limits the scaling down of the equivalent oxide thickness of the stack. These findings are explained by the spontaneous formation of lanthanum silicate and germanate species which takes place during the growth and also upon annealing. Although the ultimate film thickness scalability remains an unsolved concern, the use of an O3 -based process is demonstrated to be a suitable solution to fabricate La2 O3 films that can be successfully converted into the high- k hexagonal phase. © 2010 American Institute of Physics.

In the effort to ultimately shrink the size of logic devices towards a post-Si era, the integration of Ge as alternative channel material for high-speed p-MOSFET devices and the concomitant coupling with high permittivity dielectrics (high-k) as gate oxides is currently a key-challenge in microelectronics. However, the Ge option still suffers from a number of unresolved drawbacks and open issues mainly related to the thermodynamic and electrical compatibility of Ge substrates with high-k gate stack. Strictly speaking, two main concerns can be emphasized. On one side is the dilemma on which chemical/physical passivation is more suitable to minimize the unavoidable presence of electrically active defects at the oxide/semiconductor interface. On the other side, overcoming the SiO2 gate stack opens the route to a number of potentially outperforming high-k oxides. Two deposition approaches were here separately adopted to investigate the high-k oxide growth on Ge substrates, the molecular beam deposition (MBD) of Gd2O3 and the atomic layer deposition (ALD) of HfO2. In the MBD framework epitaxial and amorphous Gd2O3 films were grown onto GeO2-passivated Ge substrates. In this case, Ge passivation was achieved by exploiting the Ge4+ bonding state in GeO2 ultra-thin interface layers intentionally deposited in between Ge and the high-k oxide by means of atomic oxygen exposure to Ge. The composition of the interface layer has been characterized as a function of the oxidation temperature and evidence of Ge dangling bonds at the GeO2/Ge interface has been reported. Finally, the electrical response of MOS capacitors incorporating Gd2O3 and GeO2-passivated Ge substrates has been checked by capacitance–voltage measurements. On the other hand, the structural and electrical properties of HfO2 films grown by ALD on Ge by using different oxygen precursors, i.e. H2O, Hf(OtBu)2(mmp)2, and O3, were compared. Exploiting O3 as oxidizing precursor in the ALD of HfO2 is shown to play a benefi

The nature of the defects present at various Ge/GeO2 interfaces has been investigated by means of electrically detected magnetic resonance EDMR spectroscopy. GeO2 thin films were grown by atomic oxygen, ozone, and molecular oxygen exposure. The defect microstructure is sensitive to the oxidizing species, i.e., to the oxidation mechanism. Different EDMR spectra are correlated with the specific electrical response of the corresponding Ge/GeO2 metal-oxide-semiconductor structures.

The nature of the defects present at the Ge/oxide interface has been investigated by electrically detected magnetic resonance spectroscopy. In vacuo atomic oxygen exposure has been exploited to generate germanium oxide with variable composition according to the oxidation temperature. Two different kinds of interfacial defects have been identified, which correspond to the Ge dangling bonds and to an oxygen-related defect.