Academic and industry research progress in germanium nanodevices
TL;DR: Germanium-based transistors have the potential to operate at high speeds with low power requirements and might therefore be used in non-silicon-based semiconductor technology in the future.
Abstract: Silicon has enabled the rise of the semiconductor electronics industry, but it was not the first material used in such devices. During the 1950s, just after the birth of the transistor, solid-state devices were almost exclusively manufactured from germanium. Today, one of the key ways to improve transistor performance is to increase charge-carrier mobility within the device channel. Motivated by this, the solid-state device research community is returning to investigating the high-mobility material germanium. Germanium-based transistors have the potential to operate at high speeds with low power requirements and might therefore be used in non-silicon-based semiconductor technology in the future.
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TL;DR: It is found that the shape of these heterofullerenes doped by transition metals appears to be a general structural motif for both silicon and germanium clusters when mixing with phosphorus and arsenic atoms.
Abstract: Recently, metallic heterofullerenes were experimentally prepared from mixed Ge–As clusters and heavier elements of groups 14 and 15. We found that the shape of these heterofullerenes doped by transition metals appears to be a general structural motif for both silicon and germanium clusters when mixing with phosphorus and arsenic atoms. Structural identifications for MSi8P6, MSi8As6, MGe8P6, and MGe8As6 clusters, with M being a transition metal of group 6 (Cr, Mo and W), showed that most MA8E6 clusters, except for Cr-doped derivatives CrSi8As6, CrGe8P6, and CrGe8As6, exhibit a high-symmetry fullerene shape in which metal dopant is centered in a D3h A8E6 heterocage consisting of six A3E2 pentagonal faces and three A2E2 rhombus faces. The stability of the MA8E6 metallic heterofullerene is significantly enhanced by formation an electron configuration of [1S2 1P6 1D10 1F14 1G18 2S2 2P6 2D10] enclosing 68 electrons. The A8E6 heterocages give a great charge transfer (∼4 electrons) to centered dopant, establishin...
4 citations
TL;DR: Some boron-doped germanium clusters BxGe12q with x = 1, 2, 3, and 4 and q = 0, 1 were designed as stabilized double ring tubes as discussed by the authors.
Abstract: Some boron-doped germanium clusters BxGe12q with x = 1, 2, 3, and 4 and q = 0, 1 were designed as stabilized double ring tubes. While the B2Ge12 constitutes the smallest deltahedral germanium clust...
4 citations
TL;DR: In this article , the electronic properties of the PbBi compound considering the effects induced by the different supporting substrates, namely Si(111) and Ge(111), were investigated.
Abstract: Co-adsorption of Pb and Bi onto Si(111) and Ge(111) surfaces has been found to result in formation of atomic-layer PbBi compounds having similar structures. These are two co-existing crystalline PbBi phases with 2 3 × 2 3 and 2 × 2 periodicities. Using density functional theory calculations, we found that these two phases present insulating and highly anisotropic metallic systems, respectively. However, electronic structure of the metallic 2 × 2-PbBi phase on Ge(111) appears qualitatively different from that on the Si(111). We investigated electronic properties of the PbBi compound considering the effects induced by the different supporting substrates, namely Si(111) and Ge(111). As a part of comparative study, we made the chemical-bonding analysis and examined a free-standing PbBi layer inspecting the dependence of its spectral characteristics on the compressive/tensile strain. We believe that the present findings will play an important role in the development of new electronic devices fabricated in the ultimate two-dimensional limit.
4 citations
TL;DR: Of the monodentate and row-bridged bidentate structures that formed, the dative-bonded configurations were found to be more stable than the NH dissociative adsorption structures.
Abstract: We have performed density functional theory (DFT) calculations of the atomic and electronic structures of ethylenediamine on Ge(100) The two amine groups in ethylenediamine can interact with germanium surface atoms through a N–H dissociative nucleophilic reaction and/or N-dative bonding with an electron-deficient down Ge atom Of the monodentate and row-bridged bidentate structures that formed, the dative-bonded configurations were found to be more stable than the NH dissociative adsorption structures The formation of row-bridged bidentate, structures is more favorable than that of on-top or end-bridged structures In simulated STM images, the three types of row-bridged adsorption structure have characteristic features, and the row-bridged dative-bonded configuration gives rise to features due to both adsorbed ethylenediamine molecules and the underlying Ge atoms
4 citations
02 Jun 2014
TL;DR: In this paper, the phosphorus delta-doping of germanium in ultra-high vacuum is used to tune doping at high densities (>10 cm -3) in thin Ge films.
Abstract: We have demonstrated that phosphorus delta-doping of germanium in ultra-high vacuum is a promising technique to tune doping at high densities (>10
20
cm
-3
) in thin Ge films. Eventually, high doping densities on demand for photonic or electronic applications may be delivered by suitably choosing the total number of layers, tuning their separation in the δ-layer stack, and engineering the amount of P incorporated in each layer.
3 citations
References
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01 Dec 2007
TL;DR: In this paper, a 45 nm logic technology is described that for the first time incorporates high-k + metal gate transistors in a high volume manufacturing process, resulting in the highest drive currents yet reported for NMOS and PMOS.
Abstract: A 45 nm logic technology is described that for the first time incorporates high-k + metal gate transistors in a high volume manufacturing process. The transistors feature 1.0 nm EOT high-k gate dielectric, dual band edge workfunction metal gates and third generation strained silicon, resulting in the highest drive currents yet reported for NMOS and PMOS. The technology also features trench contact based local routing, 9 layers of copper interconnect with low-k ILD, low cost 193 nm dry patterning, and 100% Pb-free packaging. Process yield, performance and reliability are demonstrated on 153 Mb SRAM arrays with SRAM cell size of 0.346 mum2, and on multiple microprocessors.
973 citations
08 Dec 2003
TL;DR: In this article, the authors describe a novel strained transistor architecture which is incorporated into a 90nm logic technology on 300mm wafers, which features an epitaxially grown strained SiGe film embedded in the source drain regions.
Abstract: This paper describes the details of a novel strained transistor architecture which is incorporated into a 90nm logic technology on 300mm wafers The unique strained PMOS transistor structure features an epitaxially grown strained SiGe film embedded in the source drain regions Dramatic performance enhancement relative to unstrained devices are reported These transistors have gate length of 45nm and 50nm for NMOS and PMOS respectively, 12nm physical gate oxide and Ni salicide World record PMOS drive currents of 700/spl mu/A//spl mu/m (high V/sub T/) and 800/spl mu/A//spl mu/m (low V/sub T/) at 12V are demonstrated NMOS devices exercise a highly tensile silicon nitride capping layer to induce tensile strain in the NMOS channel region High NMOS drive currents of 126mA//spl mu/m (high VT) and 145mA//spl mu/m (low VT) at 12V are reported The technology is mature and is being ramped into high volume manufacturing to fabricate next generation Pentium/spl reg/ and Intel/spl reg/ Centrino/spl trade/ processor families
729 citations
TL;DR: In this paper, a method of controlling threading dislocation densities in Ge on Si involving graded SiGe layers and chemical-mechanical polishing (CMP) is presented.
Abstract: A method of controlling threading dislocation densities in Ge on Si involving graded SiGe layers and chemical-mechanical polishing (CMP) is presented. This method has allowed us to grow a relaxed graded buffer to 100% Ge without the increase in threading dislocation density normally observed in thick graded structures. This sample has been characterized by transmission electron microscopy, etch-pit density, atomic force microscopy, Nomarski optical microscopy, and triple-axis x-ray diffraction. Compared to other relaxed graded buffers in which CMP was not implemented, this sample exhibits improvements in threading dislocation density and surface roughness. We have also made process modifications in order to eliminate particles due to gas-phase nucleation and cracks due to thermal mismatch strain. We have achieved relaxed Ge on Si with a threading dislocation density of 2.1×106 cm−2, and we expect that further process refinements will lead to lower threading dislocation densities on the order of bulk Ge su...
620 citations
TL;DR: In this article, the opportunities and challenges of high-k/Ge MOSFETs are discussed on the basis of the material properties of Ge oxide to provide insights for future progress.
443 citations