Equivalent Doping Research Articles

Realizing Bright-Dark Dual-Field Multimode Optical Signals in Photochromic Apatite Phosphors for Security Identification.

Regulating defect distribution in inorganic phosphors is paramount for realizing multimode dual-field optical signals for high security level identification but remains an ongoing challenge. Here, we propose a strategy of equivalent anion doping and nonequivalent cation doping to successfully regulate the trap distribution and density in Ba5(PO4)3Cl:F-,Eu2+,Ce3+ (BPCF-AG) phosphors. Due to the coexistence of shallow and deep traps for different photon processes, the BPCF-AG exhibits simultaneous photochromism in a bright field and tetramode luminescence (photoluminescence, afterglow, 980 nm photostimulated luminescence, and 650/532 nm photostimulated afterglow) in a dark field. The trap roles responsible for versatile optical behaviors are investigated by thermoluminescence curves, and a reasonable mechanism is proposed. In addition, we design a series of demonstrations for security identification and information encryption based on the dual-field multimode optical signals of BPCF-AG to illustrate its potential application scenarios.

P-Doped Carbon Nanotubes As Light Absorbers and Electron Donors in Photovoltaics

Doping is a ubiquitous and powerful tool used to alter a material’s electronic properties. Conventional Si solar cells would not exist without it, and it has been used to increase the efficiency of organic and inorganic photovoltaics alike. While doped carbon nanotubes (CNTs) have been the subject of numerous spectroscopic studies, few investigations have examined their performance in photovoltaic devices. Here, we incorporate chemically p-doped CNTs into photovoltaic heterojunctions with C60. In a conventional CNT–C60 heterojunction device, photocurrent can be produced when photogenerated excitons in the CNT layer diffuse to the CNT–C60 heterointerface. The offset in conduction band energy drives dissociation of these excitons via photoelectron transfer from CNT to C60, which yields separated charges that can be collected. Our objective here was to determine the following: 1) does p-doping increase or decrease the efficiency with which excitons dissociate into electrons and holes? 2) Do p-dopants trap excitons and inhibit their diffusion to the heterointerface? 3) How efficiently can a photogenerated trion (exciton coupled to an injected hole) be dissociated to produce a photocurrent?To answer these questions, we fabricated polymer wrapped (6,5) CNT–C60 heterojunctions over a range of CNT thickness with various levels of p-doping introduced by triethyloxonium hexachloroantimonate treatment. We measured photocurrent to quantify relative photoelectron transfer efficiency for both excitons and trions and compared this to photoluminescence and transient absorbance measurements on doped CNT films. We found that p-doping decreases photocurrent because injected holes bleach the CNTs’ S11 transition and decrease the amount of light absorbed. Meanwhile, the photogenerated exciton to collected electron transfer efficiency remains unchanged for doping densities up to 50μm-1. In contrast, photoluminescence quantum yield drops by over 90% at an equivalent doping density. We attribute this disparity to the fast electron transfer at the CNT–C60 interface, which occurs on the order of femtoseconds. We also found that moderate doping can promote photocurrent at the trion peak, with a photogenerated trion to collected electron transfer efficiency about 1/4 that of the photogenerated exciton to collected electron transfer efficiency. Photocurrent at the trion absorption peak is invariant with reverse bias up to 0.3 V, despite the charged nature of the trion, supporting evidence for the immobile nature of trions. These results indicate that p-CNTs are a viable material for use in photovoltaics, albeit with weaker absorption, and that photocurrent from trions is possible, although with lower quantum efficiency. Figure 1

Controllable morphology, excellent stability and non-equivalent doping-induced optical properties of Mn4+-activated K2NaScF6 red phosphor for high-quality warm WLED

Currently, Mn4+ activated fluoride red phosphor has been widely studied to improve the optical performance of white light-emitting diode (WLED) in the field of high-efficiency lighting and wide color gamut backlight display. In this paper, a series of red-emitting K2NaScF6:Mn4+ phosphors are synthesized by a simple co-precipitation method with a non-equivalent substitution of Mn4+ for Sc3+ at room temperature. The crystal structure, morphology and elemental composition of K2NaScF6:Mn4+ phosphors prepared using different reaction conditions are systematically investigated. Interestingly, the K2NaScF6:Mn4+ phosphors exhibit narrowband red emission with low correlated color temperature (CCT), high color purity and short fluorescence lifetime. Compared to equivalent doping, the mechanism of short fluorescence lifetime caused by non-equivalent doping has also been systematically discussed. The optimal doping concentration is determined by setting a series of Mn4+ doping concentrations and the concentration quenching mechanism is analyzed. The crystal field strength (Dq), Racah parameters (B and C) and nephelauxetic ratio (β1) are calculated in detail to evaluate the crystal field environment of Mn4+ in K2NaScF6. The good water resistance of the as-prepared sample K2NaScF6:Mn4+ is verified by comparing with the commercially available phosphor K2SiF6:Mn4+. Moreover, the thermal stability is also analyzed by calculating the activation energy (Ea), chromaticity shift (ΔE) and chromaticity coordinate variation (CCV). Importantly, the as-packaged warm WLED (InGaN chip + YAG:Ce3+ + K2NaScF6:Mn4+) has excellent optical properties (CCT = 4082 K, color rendering index (CRI, Ra = 91.2) and luminous efficiency (LE) = 78.86 lm/W), and it exhibits good output stability at high drive currents. In summary, our work demonstrates that K2NaScF6:Mn4+ red phosphors possess a great potential application in warm WLED for the indoor lighting.

Entropy engineering in transition metal sulfides for thermoelectric application

Transition metal sulfides have emerged as highly promising materials in thermoelectrics owing to their economic viability and sustainable characteristics. Herein, we developed entropy-engineered sulfides based on TiS2. The process of equal doping at Ti sites resulted in a notable reduction in lattice thermal conductivity due to point defects and phase segregation induced by entropy engineering; however, it also had a substantial detrimental effect on the Seebeck coefficient. Finally, by incorporating minor doping at Ti sites with Zr, Nb and Ta, each at a concentration of 1 at%, an impressive figure of merit of 0.38 was achieved at 625 K because minor doping was able to maintain the large Seebeck coefficient while simultaneously reducing the lattice thermal conductivity. This study not only illuminates the significant role of entropy engineering in reducing lattice thermal conductivity but also sparks interest in the potential of equivalent doping at sulfur sites for future investigations.

Oxygen vacancies and electrical properties of different valence ions (W6+, Nb5+, Zr4+, Cr3+) doped Bi4Ti3O12 ceramics

Numerous literatures have attested that donor doping in BiT ceramics will inhibit the generation of oxygen vacancies to improve electrical properties, but our study detects an originality that acceptor doped into BiT ceramics can also reduce the concentrate of oxygen vacancies and raise the values of Curie temperature and piezoelectric constant. A serious BiT-based ceramics with different valence transition metal dopants of W6+, Nb5+, Zr4+, Cr3+ were prepared via traditional solid phase method, achieving a high Curie temperature of 680–699 °C and a large piezoelectric constant of 7–17 pC/N. To improve the structural and electrical properties of BiT-based ceramics, this paper researched the concentration of oxygen vacancies with charge compensation effect of ions substitution by investigating the phase composition, microstructure, dielectricity, and conductivity systematically. The results show that all transition metal dopants enter the B-site of BiT ceramics to different extent and Cr partially replace the A-site of BiT ceramics, while the relaxation behavior and conduction mechanism of these ceramics are mainly contributed by the migration of oxygen vacancies. Due to the increase in the number of free electrons formed by donor doping W6+ and Nb5+ into BiT ceramics, the reduction in the number of trapped electrons proffered by equivalent doping Zr4+ that occupied the Ti3+ position and the consumption in the vacancies of Bi and O provided by Cr3+ that occupied the A-site after Bi volatilization, the oxygen vacancies defects of the BiT-based ceramics were decreased after ions doped.

RESEARCH OF PRODUCTION TECHNOLOGY AND PROPERTIES OF THE BLADE IS MADE BY THE MINE WELDING METHOD

Problem statement. One of the main requirements for the blade is to achieve significant indicators of corrosion resistance and elasticity, the ability to withstand lateral and contact loads. Thanks to the combination of high-carbon and stainless steels with the help of pit welding, the effect of zone hardening is achieved in the subsequent heat treatment. Zone hardening technology is a combination of different hardness indicators on one knife blade, which leads to a significant increase in the elasticity and durability of the blade, reduces the risk of hardening cracks. Mine welding allows you to combine into a composite steels that have a high content of carbon (С = 0,9…1 %, С = 0,4…0,45 %) and chromium (Cr = 13…14 %), which with an ordinary electric arc method is practically impossible to do. High carbon equivalent and chromium doping complicates existing welding processes. With the appropriate modes of thermoplastic deformation, we get in the zone of forge welding a monolithic connection of two steels at the atomic level, which in itself is already a composite (combination of two materials with different properties to obtain a third starting material). Materials and methods. Etching the blade in an acid solution. To obtain blanks for blacksmithing (pit welding), we took steel bar ШХ15Ш (ТУ141594 DSTU4738:007) Ø – 20 mm, length L − 80 mm for the cutting part of the blade, steel bar 40Х13 DSTU 7838:007, for covers Ø − 20 mm, L − 150 mm. The total weight of the package is 0,42 kg. The results of the experiment. When conducting four experimental attempts to determine the tempering temperature-time regimes for a composite knife blade (ШХ15Ш in 40Х13 facings), the following parameters were obtained: 1. heating temperature 260…270 °С; 2. exposure for 1,8…2 hours; 3. cooling − air. The hardness of the blade is 58−59 HRC, the cutting part is 52−54 HRC of the coating. With such indicators, the maximum indicators of wear resistance of the cutting edge and high indicators of blade elasticity were obtained. For steel n690: 1. heating temperature for tempering 200…220 °С; 2. exposure for 1 hour; 3. cooling − air. Conclusions. Knife blades are proposed to be made by manual forging, without the use of pneumatic and hydraulic hammers, to ensure the purity of the experiment. The work includes calculations of heat treatment regimes, analysis of the microstructures of the obtained monosteel and composite, economic feasibility, advantages and disadvantages of one method of obtaining a blade blade over another.

Tailoring the electrical properties of Cu2ZnSnS4 thin film by heterovalent Al3+ doping

Kesterite Cu2ZnSnS4 (CZTS) thin film is an attractive photovoltaic material. Harmful vacancy and anti-site defects in CZTS can be reduced by equivalent doping. However, equivalent doping leads to a reduction in the carrier concentration that is essential to the built-in electric field and built-in potential of the device. In this work, we propose heterovalent Al doping to provide hole conduction in CZTS thin film. The chemical valence of doping cation Al3+ is different from that of the substituted cation Sn4+. Al-doped CZTS thin films were fabricated by magnetron sputtering and sulfurization. The Al content was controlled by the Al sputtering time of the precursor. The experimental results revealed the successful fabrication of heterovalent Al-doped CZTS with the preferred orientation of the (112) plane. The partial substitution of Sn by Al led to a right shift of the CZTS diffraction peaks. Al doping could improve the crystalline quality of CZTS, reduce the dislocation density and microstrain of CZTS, and enhance the compactness of the thin-film surface. With the increase in Al content, the distance decreased between the Fermi level and the valence band maximum of CZTS, and the hole concentration and conductivity of CZTS increased monotonously while the non-radiative recombination of carriers was suppressed. The conductivity of CZTS reached 1.47 × 102 S/cm. Therefore, heterovalent Al doping was found to be a useful method to regulate the electrical properties of CZTS thin film.

A red-emitting phosphor K5In3F14:Mn4+ and its potential application in the backlighting

A red-emitting phosphor with a short fluorescence lifetime plays an important role in LED backlighting. Herein, new red phosphor K5In3F14:Mn4+ (0.59%) with a tetragonal structure was prepared with the non-equivalent doping of Mn4+. The typical luminescent behaviors of Mn4+ can be observed from the phosphors. Different from the fluoride phosphors with the equivalent doping of Mn4+, K5In3F14:Mn4+ (0.59%) has a short decay time (2.74 ms). The white LED fabricated with K5In3F14:Mn4+ (0.59%) and commercial β-SiALON:Eu2+ emits bright white light under a 20 mA current, and its color gamut is up to 103% of the National Television System Committee (NTSC) standard value. So, K5In3F14:Mn4+ (0.59%) is a potential red component for LED backlighting.

Tailoring the electron and hole dimensionality to achieve efficient and stable metal halide perovskite scintillators

Abstract Metal halide perovskites have recently been reported as excellent scintillators for X-ray detection. However, perovskite based scintillators are susceptible to moisture and oxygen atmosphere, such as the water solubility of CsPbBr3, and oxidation vulnerability of Sn2+, Cu+. The traditional metal halide scintillators (NaI: Tl, LaBr3, etc.) are also severely restricted by their high hygroscopicity. Here we report a new kind of lead free perovskite with excellent water and radiation stability, Rb2Sn1-x Te x Cl6. The equivalent doping of Te could break the in-phase bonding interaction between neighboring octahedra in Rb2SnCl6, and thus decrease the electron and hole dimensionality. The optimized Te content of 5% resulted in high photoluminescence quantum yield of 92.4%, and low X-ray detection limit of 0.7 µGyair s−1. The photoluminescence and radioluminescence could be maintained without any loss when immersing in water or after 480,000 Gy radiations, outperforming previous perovskite and traditional metal halides scintillators.

Unveiling Mn4+ substitution in oxyfluoride phosphor Rb2MoO2F4:Mn4+ applied to wide-gamut fast-response backlight displays

Mn4+-doped fluoride red-emitting phosphors are widely used in white light-emitting diodes (WLEDs) for wide-color-gamut backlight display. However, the long fluorescence decay time (τ > 5 ms) are easy to cause image-retention while images rapidly switch compare to Eu2+-doped red phosphors (0.2–2 μs). Herein, we report a novel Rb2MoO2F4:Mn4+ (RMOF) phosphor with short fluorescence lifetime (τ < 4 ms) and characteristic zero phonon line emission, realized via equivalent doping of [MnF6]2− into [MoO2F4]2− group lattice. Theoretical calculations reveal that the formation energy of [MnF6]2− occupying [MoO2F4]2− only needs a low energy to balance the charge mismatch between Mn4+ and Mo6+. A wide color gamut (~101.6% NTSC) WLED without obvious image-retention was fabricated by using Rb2MoO2F4:Mn4+ as red component, showing a fasterswitchingspeed than the commercial K2SiF6:Mn4+ (τ > 8 ms) based LEDs. This [MnF6]2− group equivalent doping strategy would pay a way to explore Mn4+ occupation in oxy-fluoride phosphors and open a new perspective on designing short fluorescence decay time phosphors for wide color gamut fast-response displays.

Structural transition, large strain induced by B-site equivalent doping with Hf4+ ions in BNT-based ceramics

A series of HfO2-modified (Bi0.475Na0.405K0.055Li0.015)0.95Ba0.05Ti(1-x)HfxO3 (x = 0–0.015) lead-free ceramics were prepared. Results of detailed characterizations showed that the addition of HfO2 had little influence on the grain size, and all of the samples showed the pure perovskite structure. As the Hf4+ content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature, and the ceramics with x = 0.01 showed a high electro-strain of 0.295% at 6 kV/mm. Therefore, this study provides a new insight into of how the HfO2 addition influences the ferroelectric property of the BNT-based ceramics by B-site substitution.

Investigation on the Effect of Gate Dielectric and Other Device Parameters on Digital Performance of Silicene Nanoribbon Tunnel FET

In this article, silicene nanoribbon (SiNR)based tunneling field effect transistor (TFET) is investigated for low power digital applications. A comprehensive study on the role of gate dielectric and device parameters, such as drain doping, channel length of SiNR TFETs, are carried out to see the performance of digital applications. To achieve higher ION/IOFF ratio and lower subthreshold swing (SS), a detailed investigation is carried out on the equivalent oxide thickness (EOT), channel length, and doping of drain. A digital performance metric comparison of SiNR TFETs with germanium-silicon (Ge-Si), monolayer graphene nanoribbon (MLGNR), and bilayer graphene nanoribbon (BLGNR) TFETs has been performed. It is concluded that SiNR TFETs made of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gate dielectric with 0.86 nm effective oxide thickness, 0.5 mM (8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ) drain doping concentration, and 5 mM (8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ) source doping concentration exhibits lower intrinsic delay, higher ION, higher ION/IOFF ratio, and lower SS at 25 nm channel length.

Effect of bottleneck size on lithium migration in lithium garnets Li7La3Zr2O12 (LLZO)

Molecular dynamic simulations were performed on element-screened Li7La3Zr2O12 (LLZO)-equivalent doping system to reveal the effect of bottleneck (surface between the polyhedron of 24d and 96h site in cubic LLZO) size on lithium ion diffusion in this garnet-type solid electrolyte. The relationship between lithium ion diffusivity, lattice constant (volume), and bottleneck size were further studied. Herein, we found unneglectable discreteness between lattice constant (volume) and lithium ion diffusivity; beyond that, a quasi-linear relationship between bottleneck size and lithium ion diffusivity under high temperature (1000~1400 K) was unveiled. Our results show that by simply regulating the bottleneck size, the diffusion properties of lithium garnets can be further improved.

Enhanced Thermoelectric Properties of p-Type CaMg2Bi2 via a Synergistic Effect Originated from Zn and Alkali-Metal Co-doping.

Bi-based Zintl phase CaMg2Bi2 is a promising thermoelectric material. Here, we report that the high-concentration point defects induced by equivalent Zn doping on the Mg site significantly enhance phonon scattering and then suppress lattice thermal conductivity by 50% at room temperature. Subsequently, partial substitution of divalent calcium ions with alkali-ion doping (Li, Na, K) not only optimizes the electrical transport properties by increasing the carrier concentration but also further reduces the lattice thermal conductivity through crystal disorder. Finally, the synergistic effect of Zn and Li co-doping leads to a high ZT of ∼1.0 at 873 K and an average ZT of 0.6 between 300 and 873 K for Ca0.995Li0.005Mg1.9Zn0.1Bi1.98. This work demonstrates an instructive method to reduce the lattice thermal conductivity via doping at the Mg site, which has never been reported in the CaMg2Bi2 system. Moreover, high-performance Ca0.995Li0.005Mg1.9Zn0.1Bi1.98 alloy does not contain any toxic elements and expensive rare earth elements, which is of great significance for the development of environment-friendly thermoelectric materials.

Thermoelectric properties of Mn, Bi, and Sb co-doped SnTe with a low lattice thermal conductivity

Over a period, there has been extensive research on both single and binary elements co-doping in SnTe. For the first time, we have investigated the effects of ternary dopants, Mn, Bi, and Sb, in SnTe with an aim of employing their synergetic effects to improve the Seebeck coefficient, consequently to increase the power factor and to lower the lattice thermal conductivity (κlat). Pristine SnTe exhibits a high electrical conductivity of 6320 S/cm, where after Mn isovalent and Bi and Sb aliovalent substitution at the Sn site, the electrical conductivity reduced up to 1530 S/cm at room temperature. As a result of the tuning of the carrier concentration, an increased Seebeck coefficient in all samples is observed. Compared to equivalent doping proportion of each dopant, a higher power factor of ∼22 μW/cmK2 is recorded. Stronger phonon scattering resulting from mass fluctuation in the multiple dopants, grain size, embedded nanostructures in the grain, and strained Mn–rich nano–precipitates in the grain boundary results in a low lattice thermal conductivity, with the lowest value recorded being ∼0.86 W/mK at 773 K. As a result, a ZT value of ∼1 at 773 K is recorded for the Sn0.85Mn0.09Sb0.035Bi0.025Te sample, which is a 271% improvement from our pristine SnTe.

Targeted doping builds a high energy density composite piezoceramics for energy harvesting

AbstractTo build piezoceramics with high transduction coefficient (d33 × g33) is the key to improve the power generation capability of piezoelectric energy harvester. Here, a new targeted doping strategy has been proposed to significantly increase the energy density of piezoceramics. Taking the modification of 0.2Pb(Zn1/3Nb2/3)O3‐0.8Pb(Zr0.5Ti0.5)O3 (PZN‐PZT) as an example, dual functions can be achieved by introducing appropriate amount of target‐doped (Zn0.1Ni0.9)TiO3 (ZTN9) based on its pyrolysis characteristics. On the one hand, Ni2+ ions enter the perovskite matrix to replace Zn2+ ions to form equivalent doping; on the other hand, it induces the formation of 0‐3 ZnO/perovskite composite structure, and both of which promote the large increase in d33 × g33 due to the changes in the domain configuration are more conducive to the ferro‐/piezoelectricity. In all compositions, 0.67 mol% ZTN9 added specimen has a maximum value (12 433 × 10−15 m2/N) of the d33 × g33. The cantilever piezoelectric energy harvester fabricated with this material generates up to 4.50 μW/mm3 of power density at 1 g acceleration, which is capable of quickly charging a 47 μF electrolytic capacitor and then lit 135 parallel‐connected commercial blue light‐emitting diodes (LEDs), showing its important application in implementing self‐powered microsensors.

Observation of direct evolution from antiferromagnetism to superconductivity in Cu1−xLixFeAs ( 0≤x≤1.0 )

We report the structure, antiferromagnetism, and superconductivity in $\mathrm{C}{\mathrm{u}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{i}}_{x}\mathrm{FeAs}$ ($0\ensuremath{\le}x\ensuremath{\le}1.0$) samples. A direct evolution from antiferromagnetism to superconductivity is observed as increasing doping level of Li. A phase diagram is constructed to show this evolution, which features no coexistence region between superconductivity and antiferromagnetism. This behavior shows that antiferromagnetic CuFeAs can be regarded as a parent compound to the observed superconductivity by equivalent doping, which is different from the cases with other FeAs-based superconductors. Structural analyses and first-principles calculations indicate that the anion height of $\mathrm{F}{\mathrm{e}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ tetrahedral layer plays a crucial role on the physical properties. Moreover, the simple Fermi surface nesting picture adopted to explain the evolution from spin-density wave to superconductor in other FeAs-based superconductors might be not applicable to $\mathrm{C}{\mathrm{u}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{i}}_{x}\mathrm{FeAs}$.

Correlation of Frontier Orbital Level Offsets and Properties of A Series of Doped P3HTs

Event Abstract Back to Event Correlation of Frontier Orbital Level Offsets and Properties of A Series of Doped P3HTs Harold O. Lee1* and Sam-Shajing Sun1 1 Norfolk State University, United States Doping of organic polymeric semiconductors allow for a vast range of tunability of applications in electronic, thermoelectric, and optoelectronic device applications such as photovoltaic, thermoelectric, and transistor devices. In order to effectively implement doped organic semiconductors into devices, dopant-polymer interactions need to be optimized and well understood. In this study, the frontier orbital offsets between the dopant and the host organic semiconductor was systematically studied in order to understand how this offset affects the optoelectronic and thermoelectric properties of the organic semiconductor poly-3-hexyl-thiophene (P3HT). Optical spectroscopies, Seebeck coefficients, and conductivity measurements were used to probe the relationship between frontier orbital offsets and properties. Our studies reveal that at equivalent doping concentrations, the acceptor strength determines the level of oxidation within the semiconductor. As a result, as the frontier orbital level offset increases, the effect of doping become less noticeable while small or negative offsets yield enhanced property changes. Acknowledgements Department of Defense (Award # W911NF-15-1-0422) and National Science Foundation (NSF Award # HRD-1547771).

Structural Brain Imaging of Long-Term Anabolic-Androgenic Steroid Users and Nonusing Weightlifters

BackgroundProlonged high-dose anabolic-androgenic steroid (AAS) use has been associated with psychiatric symptoms and cognitive deficits, yet we have almost no knowledge of the long-term consequences of AAS use on the brain. The purpose of this study is to investigate the association between long-term AAS exposure and brain morphometry, including subcortical neuroanatomical volumes and regional cortical thickness. MethodsMale AAS users and weightlifters with no experience with AASs or any other equivalent doping substances underwent structural magnetic resonance imaging scans of the brain. The current paper is based upon high-resolution structural T1-weighted images from 82 current or past AAS users exceeding 1 year of cumulative AAS use and 68 non–AAS-using weightlifters. Images were processed with the FreeSurfer software to compare neuroanatomical volumes and cerebral cortical thickness between the groups. ResultsCompared to non–AAS-using weightlifters, the AAS group had thinner cortex in widespread regions and significantly smaller neuroanatomical volumes, including total gray matter, cerebral cortex, and putamen. Both volumetric and thickness effects remained relatively stable across different AAS subsamples comprising various degrees of exposure to AASs and also when excluding participants with previous and current non-AAS drug abuse. The effects could not be explained by differences in verbal IQ, intracranial volume, anxiety/depression, or attention or behavioral problems. ConclusionsThis large-scale systematic investigation of AAS use on brain structure shows negative correlations between AAS use and brain volume and cortical thickness. Although the findings are correlational, they may serve to raise concern about the long-term consequences of AAS use on structural features of the brain.

Electrical characterization of dry and wet processed interface layer in Ge/High-K devices

In this work, the dry and wet processed interface layers for three different p type Ge/atomic layer deposition (ALD) 1 nm-Al2O3/ALD 3.5 nm-ZrO2/ALD TiN gate stacks on 300 mm wafers were studied at low temperatures by capacitance–voltage (CV), conductance–voltage measurement, and deep level transient spectroscopy. The interface treatments were (1) simple chemical oxidation (Chemox); (2) chemical oxide removal (COR) followed by 1 nm oxide by slot-plane-antenna (SPA) plasma (COR and SPAOx); and (3) COR followed by vapor O3 treatment (COR and O3). Since low temperature measurements are more reliable, several parameters like equivalent oxide thickness, flatband voltage, bulk doping, and surface potential as a function of gate voltage are reported. Different temperature CV measurement suggests that all the samples are pinned at flat band voltage (Cit give a pseudoaccumulation region) due to large Dit (larger than 1013 cm−2/eV). Room temperature measurement indicates that superior results were observed for slot-plane-plasma-oxidation processed samples.