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In this work we present the process flow for the fabrication of un-cooled IR detectors employing surface micro-machining techniques over silicon substrates. These detectors are based on thin films deposited by plasma at low temperatures. The thermo sensing film used is an intrinsic a-Si_xGe_1-x:H film, which has demonstrated a very high temperature coefficient of resistance (TCR), and a moderated resistivity, these properties are better than those of the a-Si:H intrinsic film, which is commonly used in commercial IR devices. Two device configurations have been designed and fabricated, labeled planar and sandwich. The former is the configuration commonly used in commercial micro-bolometers, while the latter is proposed in order to reduce the high cell resistance observed in this kind of devices, without the necessity of doping the intrinsic film, which results in a decrement of the TCR and therefore in responsivity. Finally some performance characteristics of the devices studied are discussed in comparison with data reported in literature.

The economic health of the semiconductor industry requires substantial scaling of chip power, performance, and area with every new technology node that is ramped into manufacturing in two year intervals. With no direct physical link to any particular design dimensions, industry wide the technology node names are chosen to reflect the roughly 70% scaling of linear dimensions necessary to enable the doubling of transistor density predicted by Moore’s law and typically progress as 22nm, 14nm, 10nm, 7nm, 5nm, 3nm etc. At the time of this writing, the most advanced technology node in volume manufacturing is the 14nm node with the 7nm node in advanced development and 5nm in early exploration. The technology challenges to reach thus far have not been trivial. This review addresses the past innovation in response to the device challenges and discusses in-depth the integration challenges associated with the sub-22nm non-planar finFET technologies that are either in advanced technology development or in manufacturing. It discusses the integration challenges in patterning for both the front-end-of-line and back-end-of-line elements in the CMOS transistor. In addition, this article also gives a brief review of integrating an alternate channel material into the finFET technology, as well as next generation device architectures such as nanowire and vertical FETs. Lastly, it also discusses challenges dictated by the need to interconnect the ever-increasing density of transistors.

A new method for analyzing the local reduced activation energy $w(T)$ of the impurity conductivity is applied to Ga-doped $p$-Ge samples with a constant compensation ratio of $K=0.3$ reported by Zabrodskii and Andreev [Int. J. Mod. Phys. B8, 883 (1994)]. Here, the local reduced activation energy is defined as $w(T)=d(ln\sigma )/d(lnT)$, where $\sigma$ and $T$ denote conductivity and absolute temperature, respectively. The method enables us to deconvolute the $w(T)$ curve into contributions from different conduction mechanisms such as free-hole conduction, nearest-neighbor hopping (NNH) conduction and variable-range hopping (VRH) conduction. As a result, it is shown that both the power exponents of the pre-exponential factors of NNH and VRH conductivity tend to decrease with increasing impurity concentration.

Gate-All-Around (GAA) MOSFETs have been investigated as promising new device structures, and Germanium is used for its high carrier mobility. In this paper, a 3D parallel Monte Carlo simulation of GAA Ge nanowire nMOSFET with effective potential method is implemented. Compared the simulation results with classical results, we can see that the quantum effects affect on the distribution of density, velocity and energy, and they make a decrease on the drain current as well.

We present in this article a comprehensive review of the dynamical fluctuations in the atomic positions that may take place, even at very low temperatures, at the clean silicon or germanium (100) surfaces or at their (111) surfaces decorated with Sn or Ag adatoms. We also elucidate the intriguing, hitherto unexplained differences observed between the two, seemingly similar, Sn/Si(111) and Sn/Ge(111) surfaces. We also describe the surprising behaviors of silver ultrathin films grown on different semiconductor surfaces, displaying in certain cases a bcc phase, a one-dimensional quasicrystalline superstructure and/or well-defined quantum size effects.

Growth of Ge, Al and Sb on highly oriented pyrolytic graphite (HOPG) was systematically investigated using in situ scanning tunneling microscopy (STM). At room temperature (RT), three dimensional (3D) clusters of all three elements nucleate and grow at the step edges and defect sites of HOPG. The clusters of Al and Ge form chains, while Sb islands are mostly isolated. With further deposition at RT, Al clusters grow and coarsen into faceted islands with craters on the top (111) facets, whereas ramified single- and double-layer cluster islands are observed for Ge. When deposited or annealed at T ≥ 175°C, Ge forms crystallites but with randomly oriented facets. As spherical Sb islands grow beyond certain size, (111) facets appear on the top. Additionally, crystalline 2D films and 1D nanorods are observed for Sb deposited at RT. At T ≈ 100°C and higher flux, only the 2D and 1D Sb islands are formed. These different growth behaviors reflect the unique nature in which the atoms (molecules), clusters and crystallites of each element interact with HOPG surface and with each other.

Germanium was deposited onto highly oriented pyrolytic graphite (HOPG) with and without antimony in ultra-high vacuum. The surface morphology was analyzed using in situ scanning tunneling microscopy (STM) at room temperature (RT). The film grows exclusively in 3D island mode and was affected significantly by substrate defects. At initial stage, nucleation of cluster occurred at step edges and defect sites. Later, we found various types of Ge nanostructures on HOPG in different deposition conditions and stages, including cluster chains, cluster islands, nanowires, and double layer ramified islands at RT. Compact Ge islands were observed when depositing at a substrate temperature of 450 K or after an annealing at 600 K following RT deposition. In addition, the pre-deposited Sb on graphite enhances the sticking probability and suppresses the surface diffusion of Ge atoms, resulting in a significant increase in Ge cluster island density on HOPG terraces.

Zinc oxide and germanium multilayer films have been deposited on glass substrate using electron beam evaporation and resistive heating system, respectively, for alternate layers. The structural optical and electrical parameters have been investigated for the deposited films. The layer formation was confirmed by employing Rutherford back-scattering technique. Optical properties exhibit quantum confinement effect by showing the separate band gaps for ZnO and Ge. Electrical conductivity increases due to combined effect of all six layers (six alternate layers of Ge and ZnO).

Various amorphous SiO_x nanotube structures nucleated by GeO_x nanoparticles were synthesized by thermal evaporation method. The presence of Ge does not only nucleate the growth of the SiO_x nanomaterials, but also dopes them. The nanostructure morphology is affected by the substrate temperature, source temperature and GeO_x vapor density through their effect on the size and lifetime of the nucleation center. In general, low substrate temperature promotes the formation of the nanotube bundle structure with 2–3% atomic ratio of Ge doping, and high temperature produces Ge-free much less bundled nanotubes.

We investigate theoretically the Zeeman effect on the electron and hole states in quantum dots. In frame of tight-binding approach, we propose a method of calculating the g factor for localized states. The principal values of the g factor for the ground electron and hole states in the self-assembled Ge/Si quantum dot are calculated. We find the strong g factor anisotropy — the components g_xx, g_yy are one order smaller than the g_zz component, g_zz=15.71, g_xx=1.14, and g_yy=1.76. The analysis of the wave function structure shows that the g factor of hole are mainly controlled by the contribution of the state with J_z=±(3/2), where J_z is the angular momentum projection on the growth direction of the quantum dot. The g factor of localized electron in Ge/Si quantum dot is close to 2: g_zz=2.0004 and g_xx=g_yy=1.9976.

Evolution and ordering of multilayer Ge islands (up to 14 layers) on Si(001), prepared by physical vapor deposition at about 550°C; were studied using Scanning Tunneling Microscope (STM). In the growth process, it was observed that long huts split during the deposition of Si buffer layer. It can be explained as a consequence of strain due to lattice mismatch and intermixing of Si and Ge to form solid solution. Such a mechanism of splitting could lead the dots to order and uniformity in the subsequent layers. Apart from splitting of huts, the surface corrugation of Si spacer layer influences the nucleation of Ge islands in the next layer.

In this work we performed measurements of photoluminescence (PL), scanning tunneling microscopy (STM), and Rutherford backscattering (RBS) at grazing angles of incidence in a set of samples grown by molecular beam epitaxy, in which a Ge layer was deposited on a Si(001) substrate covered with a thin SiO₂ layer. Three different thicknesses for either layer were deposited: 0.5, 0.75 or 1 monolayer (ML) of SiO₂, and 0.3, 0.6 or 0.9 nm of Ge. The PL measurements for the samples with thicker layers show a broad band at ~ 0.85 eV superimposed on a dislocation related band at ~ 0.81 eV. The attribution of the high energy band to Ge islands in this sample is supported by STM and RBS measurements, as well as by PL measurements after hydrogen passivation of the sample surface. For the samples with thinner SiO₂ and Ge layers, no evidence for the formation of Ge islands was found.

This work reports on the synthesis of tin and germanium phthalocyanine complexes containing phenoxy and substituted phenoxy groups as phthalocyanine ring substituents. The compounds studied are: dichlorogermanium phthalocyanine complexes containing eight phenoxy (4a), o-methyl phenoxy (4b) or estrone (4c) groups on the ring. The corresponding dichlorotin complexes (5a, 5b and 5c) and diiodotin complex (6a) were also investigated, as well as diestrone phthalocyaninato tin (7). Germanium octaphenoxy phthalocyanine complexes undergo phototransformation rather than direct photobleaching, whereas tin octaphenoxy phthalocyanine complexes undergo a photobleaching process, which is mediated by photoreduction of the phthalocyanine ring. Tin octaphenoxy phthalocyanine complexes gave higher Φ_Δ values than the corresponding germanium complexes. Also tin phthalocyanine complexes containing an unsubstituted ring gave higher Φ_Δ values than the corresponding octaphenoxy substituted complexes. The triplet quantum yields increased with the increase in electron-donating power of the ring substituents.

The known oxophilicity of Germanium(IV) ion of Germanium(IV) phthalocyanine and porphyrins have been exploited to synthesize functionally active, "axial-bonding" -type hetero oligomers. These hetero trimers have been fully characterized by elemental analysis, FAB-MS, UV-visible, proton nuclear magnetic resonance (1D and ¹H-¹H COSY) and fluorescence spectroscopies, as well as differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data with those of the corresponding individual constituents reveals that there is no apparent π–π interactions in these "vertically" linked hetero oligomers. The fluorescence quantum yields were found to be lower of these hetero oligomers in comparison with those of the monomeric chromophores. Electronic energy transfer and photoinduced electron transfer from axial porphyrins to central metalloid phthalocyanine and photoinduced electron transfer from singlet state of axial porphyrins to central metalloid phthalocyanine is detected in these hetero oligomers.

The MAJORANA Collaboration has completed construction and is now operating an array of high purity Ge detectors searching for neutrinoless double-beta decay ($0\nu \beta \beta$) in ${}^{76}$Ge. The array, known as the MAJORANA DEMONSTRATOR, is comprised of 44 kg of Ge detectors (30 kg enriched to 88% in ${}^{76}$Ge) installed in an ultra-low background compact shield at the Sanford Underground Research Facility in Lead, South Dakota. The primary goal of the DEMONSTRATOR is to establish a low-background design that can be scaled to a next-generation tonne-scale experiment. This work reports initial background levels in the $0\nu \beta \beta$ region of interest. Also presented are recent physics results leveraging P-type point-contact detectors with sub-keV energy thresholds to search for physics beyond the Standard Model; first results from searches for bosonic dark matter, solar axions, Pauli exclusion principle violation, and electron decay have been published. Finally, this work discusses the proposed tonne-scale ${}^{76}$Ge $0\nu \beta \beta$ LEGEND experiment.

The economic health of the semiconductor industry requires substantial scaling of chip power, performance, and area with every new technology node that is ramped into manufacturing in two year intervals. With no direct physical link to any particular design dimensions, industry wide the technology node names are chosen to reflect the roughly 70% scaling of linear dimensions necessary to enable the doubling of transistor density predicted by Moore’s law and typically progress as 22nm, 14nm, 10nm, 7nm, 5nm, 3nm etc. At the time of this writing, the most advanced technology node in volume manufacturing is the 14nm node with the 7nm node in advanced development and 5nm in early exploration. The technology challenges to reach thus far have not been trivial. This review addresses the past innovation in response to the device challenges and discusses in-depth the integration challenges associated with the sub-22nm non-planar finFET technologies that are either in advanced technology development or in manufacturing. It discusses the integration challenges in patterning for both the front-end-of-line and back-end-of-line elements in the CMOS transistor. In addition, this article also gives a brief review of integrating an alternate channel material into the finFET technology, as well as next generation device architectures such as nanowire and vertical FETs. Lastly, it also discusses challenges dictated by the need to interconnect the ever-increasing density of transistors.

In this work we present the process flow for the fabrication of un-cooled IR detectors employing surface micro-machining techniques over silicon substrates. These detectors are based on thin films deposited by plasma at low temperatures. The thermo sensing film used is an intrinsic a-Si_xGe_1−x:H film, which has demonstrated a very high temperature coefficient of resistance (TCR), and a moderated resistivity, these properties are better than those of the a-Si:H intrinsic film, which is commonly used in commercial IR devices. Two device configurations have been designed and fabricated, labeled planar and sandwich. The former is the configuration commonly used in commercial micro-bolometers, while the latter is proposed in order to reduce the high cell resistance observed in this kind of devices, without the necessity of doping the intrinsic film, which results in a decrement of the TCR and therefore in responsivity. Finally some performance characteristics of the devices studied are discussed in comparison with data reported in literature.

The study of neutrinoless double beta decay is the most powerful approach to the fundamental question if the neutrino is a Majorana particle, i.e. its own anti-particle. The observation of the lepton number violating neutrinoless double beta decay would establish the Majorana nature of the neutrino. Until now neutrinoless double beta decay was not observed.

The GERmanium Detector Array, GERDA is a double beta decay experiment located at the INFN Gran Sasso National Laboratory, Italy. GERDA operates bare Ge diodes enriched in ⁷⁶Ge in liquid argon supplemented by a water shield. The exposure accumulated adds up to 21.6 kg· yr with a background level of 1.8 · 10⁻² cts/(keV·kg·yr).

The results of the Phase I of the experiment are presented and the preparation of the Phase II is briefly discussed.