Rm SiO Research Articles

Composition and electronic structure of {rm SiO}_{rm x}/{rm TiO}_{rm y}/Al passivating carrier selective contacts on n-type silicon solar cells

Carrier-selective and passivating SiO_{rm x}/TiO_{rm y} heterocontacts are an attractive alternative to conventional contacts due to their high efficiency potentials combined with relatively simple processing schemes. It is widely accepted that post deposition annealing is necessary to obtain high photovoltaic efficiencies, especially for full area aluminum metallized contacts. Despite some previous high-level electron microscopy studies, the picture of atomic-scale processes underlying this improvement seems to be incomplete. In this work, we apply nanoscale electron microscopy techniques to macroscopically well-characterized solar cells with SiO_{rm x}/TiO_{rm y}/Al rear contacts on n-type silicon. Macroscopically, annealed solar cells show a tremendous decrease of series resistance and improved interface passivation. Analyzing the microscopic composition and electronic structure of the contacts, we find that partial intermixing of the SiO_{rm x} and TiO_{rm y} layers occurs due to annealing, leading to an apparent thickness reduction of the passivating SiO_{rm x}. However, the electronic structure of the layers remains clearly distinct. Hence, we conclude that the key to obtain highly efficient SiO_{rm x}/TiO_{rm y}/Al contacts is to tailor the processing such that the excellent chemical interface passivation of a SiO_{rm x} layer is achieved for a layer thin enough to allow efficient tunneling through the layer. Furthermore, we discuss the impact of aluminum metallization on the above mentioned processes.

Determination of 1-propanol, ethanol, and methanol concentrations in water based on a one-dimensional phoxonic crystal sensor.

In this research, the photonic and phononic response of one-dimensional multilayer phoxonic crystals (PxCs) with normal incident of electromagnetic and acoustic waves is discussed. The presented design can work as a highly sensitive sensor for measuring three binary alcohol/water mixtures (i.e., 1-propanol/water, ethanol/water, and methanol/water) for a wide range of concentrations. The PxC sensor is able to detect small changes in the refractive index and longitudinal sound velocity of the alcohol/water mixture with initially neglecting the acousto-optical interaction. The sensor design is a defective structure as [$({\rm Si}/{\rm SiO}_2)^4 (\rm mixture\;wt. \%) {({{\rm SiO}_2}/{\rm Si})^4}$(Si/SiO2)4(mixturewt.%)(SiO2/Si)4]. Also, we studied the effects of changing mixture concentrations from 0 wt. % to 100 wt. % on the physio-chemical parameters and resonant mode frequency. In our results, we have achieved high performance for the three alcohol mixtures in both phononic and photonic sensors especially for low concentrations. For example, in the photonic sensor we obtained sensitivity, $Q$Q value, and figure of merit of 873 nm/RIU, 755, and ${290}\;{{\rm RIU}^{ - 1}}$290RIU-1, respectively, for methanol of concentration 10% in water. The phononic sensor showed higher results compared with the photonic sensor, as for ethanol with concentration 26.8% in water we obtained sensitivity, $Q$Q value, and figure of merit of ${37}\;{{\rm MHz/ms}^{ - 1}}$37MHz/ms-1, 1604, and ${8.4}\;{({\rm m/s})^{ - 1}}$8.4(m/s)-1, respectively. The proposed structure has different merits: operation at high temperatures, compact size, ease of fabrication, and feasibility of alcohol detection with two different methods that could be used in many chemical applications.

Ultra-broadband metamaterial absorber based on cross-shaped TiN resonators.

In this paper, a novel broadband plasmonic absorber based on cross-shaped titanium nitride (TiN) resonators in the ultraviolet, visible, and near-infrared regions is presented. The proposed perfect solar absorber consists of periodic arrays of cross-shaped TiN resonators located on a stack of ${{\rm SiO}_2}/{\rm TiN}$SiO2/TiN layers. By using the finite-difference time-domain method, the effects of variations of the thickness and radius of the elliptical metasurface resonators on the absorption are comprehensively investigated. The cross-shaped metamaterial absorber exhibits an averaged absorption of 90%, ranging from 200 to 3000 nm, and shows over 90% absorption from 200 to 2500 nm. Furthermore, the proposed absorber indicates absorption efficiency over 80% for an oblique incidence up to 50 deg for both TE- and TM-polarized light. These features make the proposed solar absorber usable in many solar-based applications, imaging, and thermal emitting.

Graphene-based hyperbolic metamaterials for a tunable subwavelength dark hollow beam.

Hyperbolic metamaterials have recently been widely investigated in nanophotonics systems. Here, we propose an alternating graphene/${{\rm SiO}_2}$SiO2 multilayer structure as an anisotropic medium with hyperbolic dispersion. When in-plane and out-of-plane effective permittivity is negative and positive, respectively, the incident beam (transverse magnetic polarization wave) can be split into two subwavelength beams, and a dark hollow beam can be achieved for circularly polarized incidence. Also, the size of the dark hollow beam can be tuned by changing the Fermi level. Our method is believed to be used as a tunable optical tweezer for controlling molecules.

Broadband graphene modulator based on a plus-shaped plasmonic slot waveguide.

A novel broadband graphene modulator based on a plus-shaped plasmonic slot waveguide (PSPSW) has been demonstrated. The designed modulator includes four square silver nanowires and a graphene-${{\rm Al}_2}{{\rm O}_3}$Al2O3-graphene layer. Four silver nanowires are separated from each other by an ${{\rm SiO}_2}$SiO2 gap layer, forming a plus-shaped slot waveguide. This modulator overcomes the challenge of polarization mismatch between the electric field of the plasmonic mode and the graphene plane. The highly confined plasmonic mode can strongly interact with the graphene sheets. The properties of three eigenmodes and the effect of the geometric parameters have been studied. By geometric optimization, this modulator could offer a high modulation depth of 1.13 dB/µm, a wide operation wavelength ranging from 1200 to 1600 nm, and a large modulation bandwidth of 95 GHz. This design may promote the development of graphene-based nanophotonic devices.

Crystal structure refinements of tetragonal (OH,F)-rich spessartine and henritermierite garnets

Cubic garnet (space group Ia\overline 3 d) has the general formula X 3 Y 2 Z 3O12, where X, Y and Z are cation sites. In the tetragonal garnet (space group I41/acd), the corresponding cation sites are X1 and X2, Y, and Z1 and Z2. In both space groups only the Y site is the same. The crystal chemistry of a tetragonal (OH,F)-rich spessartine sample from Tongbei, near Yunxiao, Fujian Province, China, with composition X (Mn2.82Fe^{2+}_{0.14}Ca0.04)Σ3 Y {Al1.95Fe^{3+}_{0.05}}Σ2 Z [(SiO4)2.61(O4H4)0.28(F4)0.11]Σ3 (Sps94Alm5Grs1) was studied with single-crystal X-ray diffraction and space group I41/acd. The deviation of the unit-cell parameters from cubic symmetry is small [a = 11.64463 (1), c = 11.65481 (2) Å, c/a = 1.0009]. Point analyses and back-scattered electron images, obtained by electron-probe microanalysis, indicate a homogeneous composition. The Z2 site is fully occupied, but the Z1 site contains vacancies. The occupied Z1 and Z2 sites with Si atoms are surrounded by four O atoms, as in anhydrous cubic garnets. Pairs of split sites are O1 with F11 and O2 with O22. When the Z1 site is vacant, a larger [(O2H2)F2] tetrahedron is formed by two OH and two F anions in the O22 and F11 sites, respectively. This [(O2H2)F2] tetrahedron is similar to the O4H4 tetrahedron in hydrogarnets. These results indicate ^{X}{{\rm Mn}^ {2+}_{3}}\,^{Y}{\rm Al}_{2}^{Z}[({\rm SiO}_{4})_{2}({\rm O}_{2}{\rm H}_{2})_{0.5}({\rm F}_{2})_{0.5}]_{\Sigma3} as a possible end member, which is yet unknown. The H atom that is bonded to the O22 site is not located because of the small number of OH groups. In contrast, tetragonal henritermierite, ideally ^{X}{\rm Ca}_{3}\,^{Y}{\rm Mn}^{3+}_{2}\,^{Z}[({\rm SiO}_{4})_{2}({\rm O}_{4}{\rm H}_{4})_1]_{\Sigma3}, has a vacant Z2 site that contains the O4H4 tetrahedron. The H atom is bonded to an O3 atom [O3—H3 = 0.73 (2) Å]. Because of O2—Mn3+—O2 Jahn–Teller elongation of the Mn3+O6 octahedron, a weak hydrogen bond is formed to the under-bonded O2 atom. This causes a large deviation from cubic symmetry (c/a = 0.9534).

Millimeter Wave Resistance of Metal-Dielectric $\text{Co}_{\rm x}(\text{SiO}_{2})_{\rm{1-x}}$ and $\text{Co}_{\rm x}(\text{Al}_{2}\text{O}_{3})_{\rm{1-x}}$ Films

Transmission and reflection of millimeter waveband electromagnetic waves have been studied for thin-film metal-dielectric $\rm Co_{x}(SiO_{2})_{1-x}$ and $\rm Co_{x}(Al_{2}O_{3})_{1-x}$ nanocomposite materials, where cobalt nanoparticles are placed inside $\rm SiO_{2}$ or $\rm Al_{2}O_{3}$ films of 100 nm thickness. The microwave properties of the nanocomposite samples with different cobalt content have been measured in the frequency ranges from 26 to 38 GHz and from 53 to 77 GHz. Frequency dependencies of transmission and reflection coefficients have been measured. Power loss in the samples has been determined. An algorithm for recovering the conductivity from the frequency dependencies of the transmission and reflection coefficients has been worked out. It has been found that the microwave conductivity increases with increasing cobalt content and differs drastically from the dc conductivity. The obtained results have been compared to the actual measurements of magnetic properties.

Radiation Response of Ce-Codoped Germanosilicate and Phosphosilicate Optical Fibers

We report an experimental investigation on the effects of Ce-codoping in determining the radiation response of germanosilicate and phosphosilicate Optical Fibers (OFs) in the UV-Visible domain and up to doses of $1~\hbox{MGy}({\rm SiO}_{2})$ . We show that the addition of Ce strongly impacts the Radiation Induced Attenuation (RIA) of both types of fibers. In the first case the radiation induced losses increase, whereas in the second one decrease. By combining the online RIA measurements with the Electron Paramagnetic Resonance (EPR) ones, we are able to infer the basic microscopic mechanisms taking place under irradiation, which involve the cerium codopant and some of the known Ge-related or P-related defects. More precisely, we found that part of the Ce atoms are incorporated in the glass matrix as ${\rm Ce}^{3 + }$ ions by the production process and act as electron donor centers under irradiation. Consequently, the concentrations of radiation induced hole centers of Ge and P are drastically reduced. The reported results give an insight into possible ways of exploiting Ce codoping to control the radiation sensitivity of the OFs. Moreover, the OFs doped with cerium and phosphorous show a strongly reduced saturation effect at high radiation doses that make them a potential candidate for RIA-based dosimetry applications in a wide range of radiation doses.

On-Line Characterization of Gamma Radiation Effects on Single-Ended Raman Based Distributed Fiber Optic Sensor

We report distributed temperature measurements based on Raman scattering performed during steady state $\gamma $ -ray irradiation at a dose rate of 1 kGy( ${\rm SiO}_{2}$ )/h and up to a total ionizing dose (TID) of $\sim 0.1 \hbox{MGy}$ . We characterize on-line the evolution of the performances of a single-ended Raman distributed temperature sensor (RDTS) during the $\gamma $ -ray exposure of different classes of commercial multimode fibers (MMFs) acting as the sensing element. RDTS is influenced by the radiation-induced attenuation (RIA) phenomena leading to both large errors in the temperature measurements and a diminution of the useful sensing length. The amplitude of the radiation-induced temperature error strongly depends on the fiber choice and on the irradiation conditions. For the single-ended RDTS operation in the targeted Cigeo application the selection of a radiation tolerant sensing fiber will be mandatory, but not sufficient, to overcome the expected severe ambient conditions around radioactive wastes. For efficient temperature sensing up to an accumulated dose of 0.1 MGy, pre-irradiation of the selected radiation resistant (RR) fibers appears also necessary to improve the sensor performances.

Effects of Air Annealing on Luminescent Properties of Cerium-Doped Lutetium Oxyorthosilicate Scintillation Ceramics

Cerium-doped lutetium oxyorthosilicate ( ${\rm Lu}_{2}{\rm SiO}_{5}$ : 0.5 mol%Ce, LSO:Ce) scintillation ceramics was fabricated by pre-sintering at $1650^\circ {\rm C}$ for 4 h in air followed by a post hot isostatic pressing (HIP) at $1600^\circ {\rm C}$ under 150 MPa for 1 h in Ar atmosphere. Luminescent and scintillation properties of the as-HIPed LSO:Ce ceramics was seriously affected by these oxygen vacancies. They were effectively filled through a post-annealing at $1300^\circ {\rm C}$ for 4 h in air. Ce ${\rm L}_{\rm III}$ edge X-ray absorption near edge structure (XANES) spectra of LSO:Ce ceramics manifest that most of Ce ions in LSO ceramics still remain Ce(III) valence state after annealing in air. Photoluminescence (PL) and PL excitation (PLE) spectra show that emission intensity of the as-HIPed LSO:Ce ceramics was about 3 times lower than that of post-annealed sample. Light yield of the post-annealed LSO:Ce ceramics reaches 2.7 times of that of the as-HIPed sample, which exceeds 3 times of the light yield of BGO crystal.

Encapsulating Ion-Solid Interactions in Metal-Oxide-Semiconductor (MOS) Devices

We report on a measurement of low energy ion irradiation effects on as-grown films of ${\rm SiO}_2$ on a Si substrate. Beams of normally incident ${\rm Na}^ + $ ions with kinetic energies of 2 keV to 5 keV were focused onto $ \sim 1900 {\rm \AA}$ ${\rm SiO}_2$ films. Aluminum top metal contacts were subsequently deposited onto these targets such that irradiated regions and unexposed (pristine) regions of the target could be compared using capacitance–voltage (C–V) measurements of individual metal-oxide-semiconductor (MOS) devices. The C–V data reveal an energy-dependent shift in the flatband voltage ( ${V_{\rm FB}}$ ) that can be returned to its near-pristine value by a low temperature anneal. An increase in the density of interface states ( ${D_{\rm it}}$ ) inferred from the C–V curves is found to have a superlinear dependence on the incident kinetic energy. These data are consistent with previously observed UV radiation effects on MOS oxides, where transferred energy leads to electron-hole pair production and the diffusion and trapping of holes throughout the oxide. Our measured trapped hole densities are compared with calculated densities, which are based on the incident ion dose and the predicted ion implantation range, to arrive at a fractional yield for hole survival and measurement within an encapsulated MOS device.

Improved n-Type 4H-SiC Epitaxial Radiation Detectors by Edge Termination

A new edge termination with ${\rm SiO}_{2}$ and ${\rm Si}_{3}{{\rm N}_4}$ passivating layers has been developed and is shown to be a very effective method for improving energy resolution of $20 ~\mu \hbox{m}$ n-type 4H-SiC epilayer Schottky barrier radiation detectors. The junction properties of the fabricated detectors before and after edge termination were studied by current-voltage (I-V) and capacitance-voltage (C-V) measurements. A thermionic emission model applied to the forward I-V characteristics showed surface barrier height of $\sim 1.4 ~\hbox{eV}$ and diode ideality factor of $\sim 1.1$ . The C-V measurements showed a doping concentration of $1.8 \times {10^{14}} ~\hbox{cm}^{ - 3}$ which ensured a fully depleted ${(\sim 20 ~\mu \hbox{m})}$ detector at bias voltages as low as $\sim 70 ~\hbox{V}$ . Alpha spectroscopy measurements revealed an improved energy resolution from $\sim 0.7 \% $ to $\sim 0.4\% $ for 5.48 MeV alpha particles. Deep level transient spectroscopy (DLTS) measurements have shown a decreased concentration of ${{\rm Z}_{1/2}}$ defect levels in detectors following edge termination.

Multi-MGy Radiation Hard CMOS Image Sensor: Design, Characterization and X/Gamma Rays Total Ionizing Dose Tests

A Radiation Hard CMOS Active Pixel Image Sensor has been designed, manufactured and exposed to X and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{60}{\rm Co}\,\, \gamma $</tex></formula> -ray sources up to several MGy of Total Ionizing Dose (TID). It is demonstrated that a Radiation-Hardened-By-Design (RHBD) CMOS Image Sensor (CIS) can still provide useful images after <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10~\hbox{MGy}({\rm SiO}_2)$</tex></formula> (i.e. 1 Grad). This paper also presents the first detailed characterizations of CIS opto-electrical performances (i.e. dark current, quantum efficiency, gain, noise, transfer functions, etc.) in the MGy range. These results show that it is possible to design a CIS with good performances even after having absorbed several MGy. Four different RHBD photodiode designs are compared: a standard photodiode design, two well known RHBD layouts and a proposed improvement of the gated photodiode design. The proposed layout exhibits the best performances over the entire studied TID range and further optimizations are discussed. Several original MGy radiation effects are presented and discussed at the device and circuit levels and mitigation techniques are proposed to improve further the radiation hardness of future Rad-Hard CIS developments for extreme TID applications (e.g. for nuclear power plant monitoring/dismantling, experimental reactors (e.g. ITER) or next generation particle physics experiments (e.g. CERN)).

Dry Etched Waveguide Laser Diode on GeOI

We demonstrate a top–top contact, dry etched mirror facet III–V waveguide laser diode grown on germanium-on-insulator (GeOI). A 3 x InGaAs/GaAs quantum well designed to lase at 985 nm was grown on a GaAs buffer, which was lattice matched to the GeOI platform in order to realize the monolithic integration of III–V electronic and photonic devices with silicon and ${\rm SiO}_{2}$ . Lasing occurred at $\sim 985$ nm with a threshold current density of $\sim 2 \; {\rm kA}/{\rm cm}^{2}$ . Pulsed measurements, and SEM and TEM characterization methods were used. The issue of heat transfer limited the performance of the laser.

Thermal Behavior of Portland Cement and Fly Ash–Metakaolin-Based Geopolymer Cement Pastes

Geopolymer specimens were prepared by combination of fly ash and metakaolin activated by sodium silicate (\({{\rm Na}_{2}{\rm SiO}_{3}}\)) and sodium hydroxide (NaOH) solutions. The effect of high temperature on the compressive strength, mass loss and shrinkage of geopolymer cement pastes and ordinary portland cement (OPC) pastes were assessed experimentally. Microstructure formation and development were characterized in terms of pore structure by mercury intrusion porosimetry. The results reveal that at temperatures exceeding \({400\,^{\circ}{\rm C}}\) geopolymer cement paste is superior to OPC paste. Firstly, the compressive strength drops rapidly for the OPC paste to practically zero strength at \({600\,^{\circ}{\rm C}}\) , while it drops slowly for the fly ash–metakaolin-based geopolymer cement paste to 46 MPa at \({1000\,^{\circ}{\rm C}}\) . Secondly, while the mass loss increases for the OPC paste, it is maintained at a constant, lower value for the geopolymer cement paste. Thirdly, shrinkage of geopolymer cement paste is at least three times smaller than that of OPC paste.

Surface Antireflection and Light Extraction Properties of GaN Microdomes

GaN microdomes were fabricated and measured as both an antireflection surface and a light extraction enhancement structure. The combination of self-assembled micro/nanosphere lithography and reactive ion etching process was used to fabricate GaN microdomes with different aspect ratios. ${\rm SiO}_{2} $ microspheres with diameters of 1000 and 500 nm, deposited on top of the GaN substrate using a dip-coating method, serve as the mask for the formation of GaN microdomes. The GaN microdome shapes and sizes were determined through control of the plasma etching conditions. The antireflection properties of the GaN microdomes with different sizes and shapes were characterized. Two different mechanisms were proposed to explain the surface reflection properties of incidence wavelength below and above GaN band gap, respectively. The trend shows that the surface reflection is reduced with the increase in the aspect ratio of the GaN microdomes for incidence wavelength above the band gap. For incidence wavelength below the band gap, the trend is totally different. Studies indicate that the microdomes are applicable not only as antireflection structures in solar cells but for enhancing light extraction in light-emitting diodes as well.

Optimum High-k Oxide for the Best Performance of Ultra-Scaled Double-Gate MOSFETs

A widely used technique to mitigate the gate leakage in the ultra-scaled metal oxide semiconductor field effect transistors (MOSFETs) is the use of high-k dielectrics, which provide the same equivalent oxide thickness (EOT) as $\rm SiO_2$, but thicker physical layers. However, using a thicker physical dielectric for the same EOT has a negative effect on the device performance due to the degradation of 2D electrostatics. In this letter, the effects of high-k oxides on double-gate (DG) MOSFET with the gate length under 20 nm are studied. We find that there is an optimum physical oxide thickness ($\rm T_{OX}$) for each gate stack, including $\rm SiO_2$ interface layer and one high-k material. For the same EOT, $\rm Al_2O_3$ (k=9) over 3 $\rm\AA$ $\rm SiO_2$ provides the best performance, while for $\rm HfO_2$ (k=20) and $\rm La_2O_3$ (k=30), $\rm SiO_2$ thicknesses should be 5 $\rm\AA$ and 7 $\rm\AA$, respectively. The effects of using high-k oxides and gate stacks on the performance of ultra-scaled MOSFETs are analyzed. While thin oxide thickness increases the gate leakage, the thick oxide layer reduces the gate control on the channel. Therefore, the physical thicknesses of gate stack should be optimized to achieve the best performance.

Development of an Optical Fiber-Based MR Compatible Gamma Camera for SPECT/MRI Systems

Optical fiber is a promising material for integrated positron emission tomography (PET) and magnetic resonance imaging (MRI) PET/MRI systems. Because its material is plastic, it has no interference between MRI. However, it is unclear whether this material can also be used for a single photon emission tomography (SPECT)/MRI system. For this purpose, we developed an optical fiber-based block detector for a SPECT/MRI system and tested its performance by combining $1.2 \times 1.2 \times 6~\hbox{mm} {{\rm Y}_2}{\rm SiO}_5$ (YSO) pixels into a $15 \times 15$ block and was coupled it to an optical fiber image guide that used was 0.5-mm in diameter with 80-cm long double clad fibers. The image guide had $22 \times 22~\hbox{mm}$ rectangular input and an equal size output. The input of the optical fiber-based image guide was bent at 90 degrees, and the output was optically coupled to a 1-in square high quantum efficiency position sensitive photomultiplier tube (HQE-PSPMT). The parallel hole, 7-mm-thick collimator made of tungsten plastic was mounted on a YSO block. The diameter of the collimator holes was 0.8 mm which was positioned one-to-one coupled to the YSO pixels. We evaluated the intrinsic and system performances. We resolved most of the YSO pixels in a two-dimensional histogram for Co-57 gamma photons (122-keV) with an average peak-to-value ratio of 1.5. The energy resolution was 38% full-width at half-maximum (FWHM). The system resolution was 1.7-mm FWHM, 1.5 mm from the collimator surface, and the sensitivity was 0.06%. Images of a Co-57 point source could be successfully obtained inside 0.3 T MRI without serious interference. We conclude that the developed optical fiber-based YSO block detector is promising for SPECT/MRI systems.

Surface Plasmon-Enhanced GaN Metal–Insulator–Semiconductor Ultraviolet Detectors With Ag Nanoislands Embedded in a Silicon Dioxide Gate Layer

GaN metal–insulator–semiconductor ultraviolet (UV) photodetectors (PDs) with silver (Ag) nanoislands on a silicon dioxide $({\rm SiO}_{2})$ gate layer were fabricated and characterized. Samples with different Ag mass thickness values were prepared on ${\rm SiO}_{2}$ /sapphire template substrates and characterized by transmission spectral to confirm the surface plasmon resonance (SPR) effect. By examining the transmission spectra of Ag nanoislands on the ${\rm SiO}_{2}$ /sapphire substrates, two transmission dips were observed in each spectrum. The transmission dip in the blue region was more significant than that in the UV region, but visible light with photon energy less than the bandgap of GaN was not absorbed to generate significant response. By introducing the Ag nanoislands, the UV-to-visible rejection ratio $(R_{{\rm UV/vis}})$ of spectral responsivity was at least ten times higher than those of PDs without Ag nanoislands. The $R_{{\rm UV/vis}}$ enhancement was mainly due to the increase in UV response caused by SPR at approximately 360 nm induced by Ag nanoislands to enhance UV-light absorption.

An Expandable &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ &lt;/tex-math&gt;&lt;/inline-formula&gt; Liner Stressor for N-Channel FinFETs

We report the demonstration of a novel ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ liner stressor to enhance drive current in Si n-channel FinFETs (N-FinFETs). ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ expands during thermal anneal due to an increase in crystallite size. A ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ liner stressor wrapping around an N-FinFET can be expanded and made to exert high tensile stress in the N-FinFET channel for drive current enhancement. Saturation drain current enhancement of ${\sim}{26\%}$ and linear drain current enhancement of ${\sim}{48\%}$ were observed for FinFETs with ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ liner stressor compared with control FinFETs without ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ , with no compromise on short-channel effects. The drain current enhancement increases with decreasing gate length. This technology was realized in FinFETs with silicon–carbon source/drain stressors and Al-incorporated NiSi contacts. ${\rm ZnS}\hbox{-}{\rm SiO}_{2}$ liner stressor could be a strain engineering option for N-FinFETs at sub-20-nm technology nodes.