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Bioelectronic implantable devices are adept at facilitating continuous monitoring of health and enabling the early detection of diseases, offering insights into the physiological conditions of various bodily organs. Furthermore, these advanced systems have therapeutic capabilities in neuromodulation, demonstrating their efficacy in addressing diverse medical conditions through the precise delivery of stimuli directly to specific targets. This comprehensive review explores developments and applications of bioelectronic devices within the biomedical field. Special emphasis is placed on the evolution of closed‐loop systems, which stand out for their dynamic treatment adjustments based on real‐time physiological feedback. The integration of Artificial Intelligence (AI) and edge computing technologies is discussed, which significantly bolster the diagnostic and therapeutic functions of these devices. By addressing elemental analyses, current challenges, and future directions in implantable devices, the review aims to guide the pathway for advances in bioelectronic devices. [ABSTRACT FROM AUTHOR]

Phase-change memory (PCM) has been considered a promising candidate for solving von Neumann bottlenecks owing to its low latency, non-volatile memory property and high integration density1,2. However, PCMs usually require a large current for the reset process by melting the phase-change material into an amorphous phase, which deteriorates the energy efficiency2–5. Various studies have been conducted to reduce the operation current by minimizing the device dimensions, but this increases the fabrication cost while the reduction of the reset current is limited6,7. Here we show a device for reducing the reset current of a PCM by forming a phase-changeable SiTex nano-filament. Without sacrificing the fabrication cost, the developed nano-filament PCM achieves an ultra-low reset current (approximately 10 μA), which is about one to two orders of magnitude smaller than that of highly scaled conventional PCMs. The device maintains favourable memory characteristics such as a large on/off ratio, fast speed, small variations and multilevel memory properties. Our finding is an important step towards developing novel computing paradigms for neuromorphic computing systems, edge processors, in-memory computing systems and even for conventional memory applications.We present a device that can reduce the phase-change memory reset current while maintaining a high on/off ratio, fast speed and small variations, representing advances for neuromorphic computing systems. [ABSTRACT FROM AUTHOR]

MXenes have been one of the most extensively investigated nonlinear optical materials at short-wave infrared (SWIR) wavelengths. Herein, we systemically investigated the electronic and optical characteristics of Nb4C3 MXene. First, the electronic and linear optical properties of Nb4C3 MXene were theoretically estimated using density functional theory calculation, thereby revealing the metallic property of Nb4C3 MXene. Through Z-scan measurements, we observed large saturable absorption of Nb4C3 MXene at 1560 and 1910 nm wavelengths. Self-focusing and self-defocusing properties were also observed at 1560 and 1910 nm wavelengths, respectively. The effective nonlinear absorption coefficient and nonlinear refractive index of Nb4C3 MXene were estimated as −(2.27 ± 0.12) × 103 cm GW−1 and (1.3 ± 0.04) × 10−2 cm2 GW−1 at 1560 nm, and −(2.73 ± 0.08) × 104 cm GW−1 and −(0.80 ± 0.01) × 10−1 cm2 GW−1 at 1910 nm. Based on the large and broadband optical nonlinearities, a single broadband saturable absorber (SA) was fabricated to generate optical pulses at SWIR wavelengths. Stable mode-locked pulses 1.66 ps at 1559.8 nm and 1.62 ps pulse duration at 1930.3 nm were generated with a single Nb4C3 MXene-based SA when incorporated in an erbium-doped fiber ring laser cavity and a thulium holmium-doped fiber cavity, respectively. This work indicates that Nb4C3 MXene can be a high-performance material platform for broadband optical devices at SWIR or broader wavelengths. [ABSTRACT FROM AUTHOR]

Integration of functional thin films onto flexible substrates is driven by the need to improve the performance and durability of flexible electronic devices. A van der Waals epitaxy technology that accomplishes the transfer of oxide or metal thin films via exfoliation or dissolution of sacrificial α‐MoO3 layers produced by sputtering is presented. The α‐MoO3 thin films, consisting of weakly bonded 2D layers, grow epitaxially on SrTiO3 (001) substrates, exhibiting mosaic domains rotated by 90°. Metallic Au films grown on the α‐MoO3 are transferred by mechanical exfoliation or by dissolving the α‐MoO3 in water at 45 °C. Spinel‐structured CoFe2O4 thin films grown on α‐MoO3 layers are easily transferred to flexible substrates via mechanical exfoliation, and the magnetic anisotropy of the transferred CoFe2O4 films is modulated by bending. [ABSTRACT FROM AUTHOR]

Remote epitaxy is a recently discovered type of epitaxy, wherein single-crystalline thin films can be grown on graphene-coated substrates following the crystallinity of the substrate via remote interaction through graphene. Although remote epitaxy provides a pathway to form freestanding membranes by controlled exfoliation of grown film at the graphene interface, implementing remote epitaxy is not straightforward because atomically precise control of interface is required. Here, we unveil the role of the graphene–substrate interface on the remote epitaxy of GaAs by investigating the interface at the atomic scale. By comparing remote epitaxy on wet-transferred and dry-transferred graphene, we show that interfacial oxide layer formed at the graphene–substrate interface hinders remote interaction through graphene when wet-transferred graphene is employed, which is confirmed by an increase of interatomic distance through graphene and also by the formation of polycrystalline films on graphene. On the other hand, when dry-transferred graphene is employed, the interface is free of native oxide, and single-crystalline remote epitaxial films are formed on graphene, with the interatomic distance between the epilayer and the substrate matching with the theoretically predicted value. The first atomic layer of the grown film on graphene is vertically aligned with the top layer of the substrate with these atoms having different polarities, substantiating the remote interaction of adatoms with the substrate through graphene. These results directly show the impact of interface properties formed by different graphene transfer methods on remote epitaxy. [ABSTRACT FROM AUTHOR]

Single‐crystalline inorganic semiconductor nanomembranes (NMs) have attracted great attention over the last decade, which poses great advantages to complex device integration. Applications in heterogeneous electronics and flexible electronics have been demonstrated with various semiconductor nanomembranes. Single‐crystalline aluminum nitride (AlN), as an ultrawide‐bandgap semiconductor with great potential in applications such as high‐power electronics has not been demonstrated in its NM forms. This very first report demonstrates the creation, transfer‐printing, and characteristics of the high‐quality single‐crystalline AlN NMs. This work successfully transfers the AlN NMs onto various foreign substrates. The crystalline quality of the NMs has been characterized by a broad range of techniques before and after the transfer‐printing and no degradation in crystal quality has been observed. Interestingly, a partial relaxation of the tensile stress has been observed when comparing the original as‐grown AlN epi and the transferred AlN NMs. In addition, the transferred AlN NMs exhibits the presence of piezoelectricity at the nanoscale, as confirmed by piezoelectric force microscopy. This work also comments on the advantages and the challenges of the approach. Potentially, the novel approach opens a viable path for the development of the AlN‐based heterogeneous integration and future novel electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

In 2004, K. S. Novoselov and A. K. Geim et al. have used sellotape to peel off the layered 2D graphite, and successfully obtained few‐layer thin graphene. Inspired by this, herein, the sellotape is initially used to exfoliate the layered Ruddlesden–Popper (RP) quasi‐2D perovskite film for efficient light‐emitting diodes application. The top surface layer of quasi‐2D perovskite film is mechanically peeled off by the sellotape without damaging the crystalline region below, which minimizes the poor conductivity issue of quasi‐2D perovskite film owing to the decreased defect density. Moreover, the exfoliated quasi‐2D film exhibits low charge traps density and enhanced energy transfer from low‐dimensional to high‐dimensional domains due to the elimination of surface defective layer and the recrystallization of quasi‐2D perovskite crystal, leading to high photoluminescence quantum yield (PLQY) up to 83.2%. Subsequently, an efficient perovskite light‐emitting diode based on the exfoliated quasi‐2D perovskite thin film is achieved with high current efficiency of 46.0 cd m−2 and excellent external quantum efficiency (EQE) up to 14.8%. [ABSTRACT FROM AUTHOR]

Mica is a group of clay minerals that are frequently used to fabricate electrical and thermal insulators and as adsorbents for the treatment of cationic pollutants. However, conventional subtractive manufacturing has the drawback of poor three-dimensional (3D) shape control, which limits its application. In this study, we propose digital light processing (DLP)-based additive manufacturing (AM) as one of the most effective ways to address this drawback. Two major challenges for the ceramic DLP process are the production of a homogeneous and stable slurry with the required rheological properties and the maintenance of printing precision. The mica green body was fabricated using a 53 vol.% solid loading slurry through DLP, which exhibited good dimensional resolution under an exposure energy dose of 10 mJ/cm2. The precise, complex 3D structure was maintained without any defects after debinding and sintering at 1000 °C. The use of ceramic AM to overcome the shape-control limitations of mica demonstrated in this study offers great potential for expanding the applications of mica. [ABSTRACT FROM AUTHOR]

Cross‐point arrays of analog synaptic devices are expected to realize neuromorphic computing hardware for neural network computations with compelling speed boost and superior energy efficiency, as opposed to the conventional hardware based on the von Neumann architecture. To achieve desired characteristics of analog synaptic devices for fully parallel vector–matrix multiplication and vector–vector outer‐product updates, metal‐oxide based electrochemical random‐access memory (ECRAM) is proposed as a promising synaptic device due to its complementary metal‐oxide‐semiconductor‐compatibility and outstanding synaptic characteristics over other non‐volatile memory candidates. In this work, ECRAM devices with 3D vertical structure is fabricated to demonstrate a minimal 4F2 cell size, highly scalable channel volume and low programming energy, providing optimized synaptic device performance and characteristics as well as high integrity as a cross‐point array. Various weight‐update profiles of the vertical ECRAM devices are obtained by adjusting programming voltage pulses, exhibiting trade‐offs among dynamic range, linearity, symmetry, and update deviation. Based on simulation with advanced algorithms for analog cross‐point array and neural network designs, the potential of vertical ECRAM for high‐density array is evaluated. Simulation studies suggest that the neuromorphic computing performance can be improved further by balancing the weight update characteristics of vertical ECRAM. [ABSTRACT FROM AUTHOR]

Illite is a group of clay minerals that are expected to be widely used in catalyst fabrication, radioactive element adsorption, and so forth, due to its excellent adsorption properties. However, the shape control limitation of the illite product should be overcome to maximize its utilization and properties. We herein propose additive manufacturing (AM) as one of the best solutions to solve this structural drawback. Digital light processing (DLP) technology with the film‐type of the material supplying system was adapted instead of the general vat‐type DLP system to increase illite printability. The photo‐curability and printability of illite‐contained photocurable suspension were optimized. The color effect due to different ferric oxide content in yellow‐ and white‐illite which influence the photopolymerization process also adjusted thoroughly. White illite showed better photo‐curability and could be increased solid loading than yellow illite. The defect‐free illite products with three‐dimensional complex structures, which cannot be produced by typical ceramic processes, were obtained by DLP technology for both yellow‐ and white‐illite after sintering at 1100°C. The overcoming of shape control limitation of illites by ceramic AM proved in this study has excellent potential for expanding illite utilities in various applications. [ABSTRACT FROM AUTHOR]

Several groups present their efforts on understanding the roles of 2D buffer layer on van der Waals or remote epitaxy, or engineering the 2D/3D interface for designing epitaxy conditions. We are pleased to present a special topic issue on Novel Epitaxy of Functional Materials. Accordingly, several advanced approaches[[1], [3], [5]] have been developed, such as low-temperature buffer approach, lattice-engineered buffer approach, metamorphic buffer approach, epitaxial lateral overgrowth, domain-matched epitaxy, van der Waals epitaxy, and remote epitaxy. [Extracted from the article]

Understanding lattice deformations is crucial in determining the properties of nanomaterials, which can become more prominent in future applications ranging from energy harvesting to electronic devices. However, it remains challenging to reveal unexpected deformations that crucially affect material properties across a large sample area. Here, we demonstrate a rapid and semi-automated unsupervised machine learning approach to uncover lattice deformations in materials. Our method utilizes divisive hierarchical clustering to automatically unveil multi-scale deformations in the entire sample flake from the diffraction data using four-dimensional scanning transmission electron microscopy (4D-STEM). Our approach overcomes the current barriers of large 4D data analysis without a priori knowledge of the sample. Using this purely data-driven analysis, we have uncovered different types of material deformations, such as strain, lattice distortion, bending contour, etc., which can significantly impact the band structure and subsequent performance of nanomaterials-based devices. We envision that this data-driven procedure will provide insight into materials' intrinsic structures and accelerate the discovery of materials. [ABSTRACT FROM AUTHOR]

Epitaxial lift-off techniques, which aim to separate ultrathin single-crystalline epitaxial layers off of the substrate, are becoming increasingly important due to the need of lightweight and flexible devices for heterogeneously integrated ultracompact semiconductor platforms and bioelectronics. Remote epitaxy is a relatively newly discovered epitaxial lift-off technique that allows substrate-seeded epitaxial growth of ultrathin films through few layers of graphene. This universal epitaxial lift-off technique allows freestanding single-crystal membrane fabrication very quickly at low cost. However, the conventional method of remote epitaxy requires transfer of graphene grown on another substrate to the target single-crystalline substrate, which results in organic and metallic residues as well as macroscopic defects such as cracks and wrinkles, significantly reducing the yield of remote epitaxy. Here, we show that direct growth of thick graphene on the target single-crystalline substrate (SrTiO3 for this study) followed by atomic layer etching (ALE) of the graphene layers create a defect- and residue-free graphene surface for high yield remote epitaxy. We find that the ALE efficiently removes one atomic layer of graphene per cycle, while also clearing multi-dots (clumps of carbon atoms) that form during nucleation of the graphene layers. Our results show that direct-grown graphene on the desired substrate accompanied by ALE might potentially be an ideal pathway toward commercialization of remote epitaxy. [ABSTRACT FROM AUTHOR]

Ceramic 3D printing based on stereolithography is an excellent alternative to overcome drawbacks of conventional subtractive manufacturing for 3D shape control. Optimization of photocurable ceramic slurry is one of the most essential conditions to achieve favorable 3D printed structures using SL. Homogeneity of ceramic particle dispersion in photocurable resin is particularly important to optimize ceramic suspension. Dispersant plays a significant role in increasing homogeneity. Dispersant in photocurable ceramic resin has an additional effect on photocurability and integrity of 3D printed green body. We herein discuss how dispersants influence 3D printing conditions based on stereolithography using various commercially available dispersants of BYK series such as BYK103, BYK111, BYK180, BYK182, and BYK2001. Both BYK111 and BYK180 showed better performances than others because of their lower volatilities under general temperature condition during a printing process. Both solubility and decomposition temperature of dispersants largely influenced the structural quality after washing and debinding processes. This study provides worthy information to design photocurable ceramic suspension for various types of ceramic materials. [ABSTRACT FROM AUTHOR]

The III–V InP/InGaAsP/InGaAs material family is important for photonic devices due to its optical emission and absorption in the 1.55 and 1.3 μm telecommunication bands for optical interconnects. However, InGaAsP/InGaAs generally suffer from relatively high surface recombination velocity—compared to Si [Das et al., in 2020 47th IEEE Photovoltaic Specialists Conference (PVSC) (IEEE, Calgary, AB, 2020), pp. 1167–1170] and InP [Joyce et al., Nano Lett. 12, 5325–5330 (2012)], which reduces the efficiency and can increase the noise in nanophotonic devices. Here, we demonstrate an efficient method to passivate the surface using a combination of sulfur-saturated ammonium sulfide and atomic layer deposition. After annealing, the surface passivation led to a surface recombination velocity as low as 45 cm/s, corresponding to a > 180 × increase in the photoluminesence of a nanoscale light-emitting device with 200 nm width. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SAC) can boost the intrinsic catalytic activity of hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). However, the challenge remains due to the complex synthesis process and insufficient stability. A sustainable approach is applied to synthesizing SACs through laser irradiation and gaining mesoporous graphene oxide (MGO). The surface dangling bonds of nitrogen‐doped MGO (NMGO) extract metal atoms species from Co or Fe metal foams and convert them to SAC via an appropriate synthesis approach. Notably, the Co‐NMGO electrocatalyst requires low potentials of 146 mV to convey a current density of 10 mA cm−2 towards HER. Similarly, the Fe‐NMGO electrocatalyst offers an onset of 0.79 V towards ORR in acidic solution. The individual metal atoms are confirmed via aberration‐corrected scanning transmission electron microscopy, and X‐ray absorption near‐edge structure and extended X‐ray absorption fine structure. Density functional theory calculations by applying the grand canonical potential kinetics model revealed that Co‐NMGO shows the optimum free reaction energy of −0.17 eV at −0.1 V for HER, and Fe‐NMGO has less limiting potential than that of Co‐NMGO for ORR case. This work opens a new approach towards the synthesis of SAC and its mechanistic understandings. [ABSTRACT FROM AUTHOR]

Nonlinear oxides such as LiNbO3 have found many applications in both conventional electro-optics and quantum optics. In this work, we demonstrate the van der Waals and remote epitaxy of LiNbO3 films on muscovite mica and graphene-buffered sapphire, respectively, by pulsed laser deposition. Structural analysis shows that the epitaxial relation in van der Waals epitaxy is LiNbO3 (0001) || mica (001) and LiNbO3 [ 01 1 ¯ 0 ] || mica [010] with LiNbO3 [ 10 1 ¯ 0 ] || mica [010], a 60°-rotated twin structure. The relation in remote epitaxy is LiNbO3 (0001) || sapphire (0001) and LiNbO3 [ 01 1 ¯ 0 ] || sapphire [ 01 1 ¯ 0 ] with twin structure LiNbO3 [ 1 ¯ 010 ] || sapphire [ 01 1 ¯ 0 ]. Furthermore, in remote epitaxy, Raman scattering analysis confirms the existence of graphene after deposition. Finally, we find that the oxygen partial pressure influences the presence of impurity phases significantly. The successful demonstration of van der Waals and remote epitaxy promises the feasibility of developing thin film LiNbO3 on demanded substrates toward scalable electro-optics. [ABSTRACT FROM AUTHOR]

9, 061101 (2021).10.1063/5.0049306 15 K. S. Kim, J. E. Kang, P. Chen, S. Kim, J. Ji, G. Y. Yeom, J. Kim, and H. S. Kum, APL Mater. Bae, H. Kum, W. Kong, Y. Kim, C. Choi, B. Lee, P. Lin, Y. Park, and J. Kim, Nat. Mixed-dimensional heterostructures formed by combining materials of different dimensionality offer diverse multi-functionality that cannot be otherwise obtained by pure 0D, 1D, 2D, or 3D materials.[[1], [3], [5]] The discontinuous changes in the energy dependence of the density of states and the degree of electrostatic screening across mixed-dimensional heterointerfaces substantially alter the electrical, magnetic, optical, and thermal properties, thereby presenting new and/or improved functionalities in applied technologies.[[7], [9], [11]] This special issue presents the latest research results for mixed-dimensional heterostructures, including synthesis, characterization, theory, and applications in electronics and photonics. [Extracted from the article]

Defect-passivation functional groups have been extensively explored in perovskite solar cells (PSCs) in recent years; however, most of these groups were organic, and the integration of inorganic functional groups with organic matrixes bearing other functions has rarely been reported. Here, to demonstrate the effectiveness of this integration, the combination of an inorganic group, K+ ion, and an organic conjugated polyelectrolyte (CPE) matrix which serves as a hole transporting material (HTM) is attempted. The resulting CPE material TB(K) presents much stronger abilities for defect-passivation and hole-extraction, and thus yields a much increased power conversion efficiency (PCE) of 20.01% and increased long-term stability when applied to inverted PSC devices compared with its control polymer TB(Na), where only the inorganic cations are varied from a defect-passivation group to a common one. [ABSTRACT FROM AUTHOR]

Thick films of polycrystalline silicon for solar cells can be made by crystallization of amorphous silicon. Due to the high internal stress of amorphous silicon films, deposition of such thick films is challenging. In this paper, we investigate the failure behavior of thick amorphous silicon films. Depending on the deposition method of amorphous silicon films, they can be cracked or delaminated. While nonhydrogenated amorphous silicon films deposited by an evaporator are cracked when the accumulated strain in thick films reaches a critical point, hydrogenated amorphous silicon films deposited by plasma enhanced chemical vapor deposition are delaminated from the substrate. Critical cracking/delamination thicknesses of amorphous silicon films are theoretically derived and excellent agreement with experimental results is shown. [ABSTRACT FROM AUTHOR]

Resistive random-access memories are promising analog synaptic devices for efficient bio-inspired neuromorphic computing arrays. Here we first describe working principles for phase-change random-access memory, oxide random-access memory, and conductive-bridging random-access memory for artificial synapses. These devices could allow for dense and efficient storage of analog synapse connections between CMOS neuron circuits. We also discuss challenges and opportunities for analog synaptic devices toward the goal of realizing passive neuromorphic computing arrays. Finally, we focus on reducing spatial and temporal variations, which is critical to experimentally realize powerful and efficient neuromorphic computing systems. [ABSTRACT FROM AUTHOR]

Epitaxy-the growth of a crystalline material on a substrate-is crucial for the semiconductor industry, but is often limited by the need for lattice matching between the two material systems. This strict requirement is relaxed for van der Waals epitaxy, in which epitaxy on layered or two-dimensional (2D) materials is mediated by weak van der Waals interactions, and which also allows facile layer release from 2D surfaces. It has been thought that 2D materials are the only seed layers for van der Waals epitaxy. However, the substrates below 2D materials may still interact with the layers grown during epitaxy (epilayers), as in the case of the so-called wetting transparency documented for graphene. Here we show that the weak van der Waals potential of graphene cannot completely screen the stronger potential field of many substrates, which enables epitaxial growth to occur despite its presence. We use density functional theory calculations to establish that adatoms will experience remote epitaxial registry with a substrate through a substrate-epilayer gap of up to nine ångströms; this gap can accommodate a monolayer of graphene. We confirm the predictions with homoepitaxial growth of GaAs(001) on GaAs(001) substrates through monolayer graphene, and show that the approach is also applicable to InP and GaP. The grown single-crystalline films are rapidly released from the graphene-coated substrate and perform as well as conventionally prepared films when incorporated in light-emitting devices. This technique enables any type of semiconductor film to be copied from underlying substrates through 2D materials, and then the resultant epilayer to be rapidly released and transferred to a substrate of interest. This process is particularly attractive in the context of non-silicon electronics and photonics, where the ability to re-use the graphene-coated substrates allows savings on the high cost of non-silicon substrates. [ABSTRACT FROM AUTHOR]

Nanometer‐scale‐thick Al2O3 thin films grown by atomic layer deposition are implemented as an effective interface‐passivation strategy for improving Cu2ZnSn(S,Se)4‐based thin‐film solar cell device performance. Photoluminescence characterization indicates that the enhancement originates from improved interface quality of the solar cell devices. [ABSTRACT FROM AUTHOR]

A method of forming cubic phase (zinc blende) GaN (referred as c-GaN) on a CMOS-compatible on-axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h-GaN) and possess very high polarization fields (∼MV/cm) along the common growth direction of <0001>. Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization-free along the common growth direction of <001>, however, this phase is thermodynamically unstable, requiring low-temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano-groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress-free, and low-defectivity c-GaN on CMOS-compatible on-axis Si. These results suggest that epitaxial growth conditions and nano-groove pattern parameters are critical to obtain such high quality c-GaN. InGaN/GaN multi-quantum-well structures grown on c-GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology. [ABSTRACT FROM AUTHOR]

Full activation of n-type dopant in germanium (Ge) reaching to its solid solubility has never been achieved by using ion implantation doping technique. This is because implantation of dopants always leaves defects such as vacancy and interstitials in the Ge crystal. While implantation-induced defects are electrically neutral for the most of semiconductor materials, they are electrically positive for Ge resulting in compensation of n-type dopants. In this Letter, we verified that 5 × 1019 P/cm3 is the maximum active concentration, which can be fully activated in germanium 'without leaving implantation damage' per implantation/annealing cycle. The repetition of implantation and annealing of phosphorous (P) with the concentration of 5 × 1019 cm-3 leads to the activation of 1 × 1020 P/cm3 close to its solid solubility limit of 2 × 1020 P/cm3. [ABSTRACT FROM AUTHOR]

Obtaining heavily-doped n-type germanium (Ge) is difficult since n-type dopant activation in Ge is limited to less than 5×1019 cm-3 which is far below the solid solubility limit of phosphorus (P) in Ge. Such poor activation has limited the rectifying properties of n+/p Ge diodes. This work is aimed at understanding the challenge of forming highly rectifying n+/p diode as well as enhancing rectification of n+/p diode by using antimony (Sb) and P coimplantation process. Enhanced n+ doping of greater than 1020 cm-3 in Ge obtained by Sb/P codoping results in enhanced rectification in Ge n+/p junction diode. [ABSTRACT FROM AUTHOR]

A method for fabricating tensile-strained SiGe films via the oxidation of porous Si substrates with thin SiGe overlayers is reported. A 100 nm thick Si0.77Ge0.23 film on a porous Si substrate is fabricated through self-limiting anodization of a heavily doped p-type Si substrate with an epitaxially grown intrinsic Si0.77Ge0.23 overlayer. The pseudomorphic Si0.77Ge0.23 film originally under 0.94% compressive strain on the porous Si substrate becomes completely relaxed by low temperature (500 °C) oxidation of the porous Si substrate. Continued oxidation introduces an additional 0.71% tensile strain in the Si0.77Ge0.23 layer without the introduction of dislocations or cracks. [ABSTRACT FROM AUTHOR]

A method to fabricate strained Si films is reported via the oxidation of a thin Si film on a porous Si substrate. The Si film can be put under tensile stress in a controllable fashion through the expansion of the porous Si upon low temperature oxidation. The thin Si layer on porous Si substrate can be fabricated using a self-limiting anodization of epitaxially grown intrinsic Si on a heavily doped p-type Si substrate. Tensile strain of up to ∼1% is observed in 100 nm thick Si films, making it suitable for the various device applications based on strained Si. [ABSTRACT FROM AUTHOR]

Gallium nitride is integrated on a CMOS‐compatible Silicon (100) substrate. On page 4492, C. Bayram et al. demonstrate thermodynamically stable, stress‐free, lowdefectivity GaN. The issue of lattice‐ and thermalmismatch between GaN and Si is reconciled through a new mask‐free local‐area epitaxy. Novel U‐shaped nanogroove patterns are also demonstrated, enabling polarization‐free cubicphase GaN. (In)GaN‐based multi‐quantum‐well structures on such polarization‐free GaN/Si templates offer an ideal roadmap for (integrated) photonic devices. [ABSTRACT FROM AUTHOR]