Both biological and engineering approaches have contributed significantly to the recent advance in the field of mechanobiology. Collaborating with biologists, bio-engineers and materials scientists have employed the techniques stemming from the conventional semiconductor industry to rebuild cellular milieus that mimic critical aspects of in vivo conditions and elicit cell/tissue responses in vitro. Such reductionist approaches have help to unveil important mechanosensing mechanism in both cellular and tissue level, including stem cell differentiation and proliferation, tissue expansion, wound healing, and cancer metastasis. In this mini-review, we discuss various microfabrication methods that have been applied to generate specific properties and functions of designer substrates/devices, which disclose cell-microenvironment interactions and the underlying biological mechanisms. In brief, we emphasize on the studies of cell/tissue mechanical responses to substrate adhesiveness, stiffness, topography, and shear flow. Moreover, we comment on the new concepts of measurement and paradigms for investigations of biological mechanotransductions that are yet to emerge due to on-going interdisciplinary efforts in the fields of mechanobiology and microengineering.

To have a high quality experimental growth of crystals, understanding the equilibrium crystal shape (ECS) in different thermodynamic growth conditions is important. The factor governing the ECS is usually the absolute surface formation energies for surfaces (or edges in 2D) in different orientations. Therefore, it is necessary to obtain an accurate value of these energies in order to give a good explanation for the observation in growth experiment. Historically, there have been different approaches proposed to solve this problem. This paper is going to review these representative literatures and discuss the pitfalls and advantages of different methods.

Nowadays, inorganic CsPbI₃ perovskite solar cells (PSCs) have become one of the most attractive research hotspots in photovoltaic field for its superior chemical stability and excellent photo-electronic properties. Since the first independent report in 2015, the power conversion efficiency (PCE) of CsPbI₃ based PSCs has sharply increased from 3.9% to 19.06%. Importantly, during the developing process of CsPbI₃ PSCs, HI hydrolysis-derived intermediate plays an important role: from stabilizing the crystal structure, optimizing the fabricated film to boosting the device performance. In this review, the different crystal and electronic structures of CsPbI₃ are introduced. We then trace the history and disputes of HI hydrolysis-derived intermediate to make this review more logical. Meanwhile, we highlight the functions of HI hydrolysis-derived intermediate, and systematically summarize the advanced works on CsPbI₃ PSCs. Finally, the bottlenecks and prospects are revealed to further increase the CsPbI₃ PSCs performance.

The distinguished electronic and optical properties of lead halide perovskites (LHPs) make them good candidates for active layer in optoelectronic devices. Integrating LHPs and two-dimensional (2D) transition metal dichalcogenides (TMDs) provides opportunities for achieving increased performance in heterostructured LHPs/TMDs based optoelectronic devices. The electronic structures of LHPs/TMDs heterostructures, such as the band offsets and interfacial interaction, are of fundamental and technological interest. Here CsPbBr₃ and MoSe₂ are taken as prototypes of LHPs and 2D TMDs to investigate the band alignment and interfacial coupling between them. Our GGA-PBE and HSE06 calculations reveal an intrinsic type-II band alignment between CsPbBr₃ and MoSe₂. This type-II band alignment suggests that the performance of CsPbBr₃-based photodetectors can be improved by incorporating MoSe₂ monolayer. Furthermore, the absence of deep defect states at CsPbBr₃/MoSe₂ interfaces is also beneficial to the better performance of photodetectors based on CsPbBr₃/MoSe₂ heterostructure. This work not only offers insights into the improved performance of photodetectors based on LHPs/TMDs heterostructures but it also provides guidelines for designing high-efficiency optoelectronic devices based on LHPs/TMDs heterostructures.

Aligned SnS nanowires arrays were grown via a simple chemical vapor deposition method. As-synthesized SnS nanowires are single crystals grown along the [111] direction. The single SnS nanowire based device showed excellent response to near infrared lights with good responsivity of 267.9 A/W, high external quantum efficiency of 3.12 × 10⁴ % and fast response time. Photodetectors were built on the aligned SnS nanowire arrays, exhibiting a light on/off ratio of 3.6, and the response and decay time of 4.5 and 0.7 s, respectively, to 1064 nm light illumination.

Nanofibers/nanowires with one-dimension (1D) nanostructure or well-patterned microstructure have shown distinctly advantages in flexible and stretchable sensor fields, owing to their remarkable tolerance against mechanical bending or stretching, outstanding electronic/optoelectronic properties, good transparency, and excellent geometry. Herein, latest summaries in the unique structure and properties of nanofiber/nanowire function materials and their applications for flexible and stretchable sensor are highlighted. Several types of high-performance nanofiber/nanowire-based flexible pressure and stretchable sensors are also reviewed. Finally, a conclusion and prospect for 1D nanofiber/nanowires-based flexible and stretchable sensors are also intensively discussed. This summary offers new insights for the development of flexible and stretchable sensor based 1D nanostructure in next-generation flexible electronics.

Due to the excellent optoelectronic properties, fast response time, outstanding power efficiency and high stability, micro-LED plays an increasingly important role in the new generation of display technology compared with LCD and OLED display. This paper mainly introduces the preparation methods of the GaN-based micro-LED array, the optoelectronic characteristics, and several key technologies to achieve full-color display, such as transfer printing, color conversion by quantum dot and local strain engineering.

The perovskite material has many superb qualities which allow for its remarkable success as solar cells; flexibility is an emerging field for this technology. To encourage commercialization of flexible perovskite solar cells, two main areas are of focus: mitigation of stability issues and adaptation of production to flexible substrates. An in-depth report on stability concerns and solutions follows with a focus on Ruddlesden-Popper perovskites. Roll to roll processing of devices is desired to further reduce costs, so a review of flexible devices and their production methods follows as well. The final focus is on the sustainability of perovskite solar cell devices where recycling methods and holistic environmental impacts of devices are done.

With the advent of human-friendly intelligent life, as well as increasing demands for natural and seamless human-machine interactions, flexibility and wearability are among the inevitable development trends for electronic devices in the future. Due to the advantages of rich physicochemical properties, flexible and stretchable inorganic oxide thin-film electronics play an increasingly important role in the emerging and exciting flexible electronic field, and they will act as a critical player in next-generation electronics. However, a stable strategy to render flexibility while maintaining excellent performance of oxide thin films is the most demanding and challenging problem, both for academic and industrial communities. Thus, this review focuses on the latest advanced strategies to achieve flexible inorganic oxide thin-film electronics. This review emphasizes the physical transferring strategies that are based on mechanical peeling and the chemical transferring strategies that are based on sacrificial layer etching. Finally, this review evaluates and summarizes the merits and demerits of these strategies toward actual applications, concluding with a future perspective into the challenges and opportunities for the next-generation of flexible inorganic oxide thin-film electronics.

Current electronics are driven by advanced microfabrication for fast and efficient information processing. In spite of high performance, these wafer-based devices are rigid, non-degradable, and unable to autonomous repair. Skin-inspired electronics have emerged as a new class of devices and systems for next-generation flexible and wearable electronics. The technology gains inspiration from the structures, properties, and sensing mechanisms of the skin, which may find a broad range of applications in cutting-edge fields such as healthcare monitoring, human-machine interface, and soft robotics/prostheses. Practical demands have fueled the development of electronic materials with skin-like properties in terms of stretchability, self-healing capability, and biodegradability. These materials provide the basis for functional sensors with innovative and biomimetic designs. Further system-level integrations and optimizations enable new forms of electronics for real-world applications. This review summarizes recent advancements in this active area and speculates on future directions.

Soft robots complement the existing efforts of miniaturizing conventional, rigid robots, and have the potential to revolutionize areas such as military equipment and biomedical devices. This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli, such as heat, solvent, light, electric field, magnetic field, and mechanical field. Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots. Existing studies mainly focus on four key aspects: reconfiguration mechanisms, fabrication schemes, deformation control principles, and practical applications. This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli, with a number of impressive examples, demonstrating high degrees of deformation complexities and varied multi-functionalities. The latest progress based on the development of new materials and unique design concepts is highlighted. An outlook on the remaining challenges and open opportunities is provided.

Aluminum nitride (AlN) has attracted a great amount of interest due to the fact that these group III–V semiconductors present direct band gap behavior and are compatible with current micro-electro-mechanical systems. In this work, three dimensional (3D) AlN architectures including tubes and helices were constructed by rolling up AlN nanomembranes grown on a silicon-on-insulator wafer via magnetron sputtering. The properties of the AlN membrane were characterized through transmission electron microscopy and X-ray diffraction. The thickness of AlN nanomembranes could be tuned via the RIE thinning method, and thus micro-tubes with different diameters were fabricated. The intrinsic strain in AlN membranes was investigated via micro-Raman spectroscopy, which agrees well with theory prediction. Whispering gallery mode was observed in AlN tubular optical microcavity in photoluminescence spectrum. A postprocess involving atomic layer deposition and R6G immersion were employed on as-fabricated AlN tubes to promote the Q-factor. The AlN tubular micro-resonators could offer a novel design route for Si-based integrated light sources. In addition, the rolled-up technology paves a new way for AlN 3D structure fabrication, which is promising for AlN application in MEMS and photonics fields.

Negative capacitance FinFET (NC-FinFET) has a promising developmental prospect due to its superior performance in SS < 60 mV/dec (subthreshold swing), especially in SRAM. Noise margin is an important metric to evaluate the performance for SRAM, together with static leakage, read speed, etc. In this paper, we study the effects of the variation of ferroelectric material (thickness, polarization), FinFET critical physical parameters (fin number, channel length) and some ambient factors (working temperature, supply voltage) on the performance of NC-FinFET SRAM within the reasonable fluctuation tolerance range. The SRAM bit cell is analyzed with a basic 6T structure. The impact of fin number and channel length for NC-FinFET SRAM is different from that of conventional FinFETs. Additionally, the ferroelectric material and some other factors are assessed in detail.

A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm² and breakdown voltage exceeding 1.5 kV is designed and fabricated. Numerical simulations are carried out to optimize the electric field strength in gate oxide and at the surface of the semiconductor material in the edge termination region. Additional n-type implantation in JFET region is implemented to reduce the specific on-resistance. The typical leakage current is less than 1 μA at V_DS = 1.4 kV. Drain-source current reaches 50 A at V_DS = 0.75 V and V_GS = 20 V corresponding to an on-resistance of 15 mΩ. The typical gate threshold voltage is 2.6 V.

A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper. The device features an integrated Schottky barrier diode and an L-shaped P⁺ shielding region beneath the gate trench and aside one wall of the gate trench (S-TMOS). The integrated Schottky barrier diode works as a free-wheeling diode in reverse recovery and reverse conduction, which significantly reduces reverse recovery charge (Q_rr) and reverse turn-on voltage (V_F). The L-shaped P⁺ region effectively shields the coupling of gate and drain, resulting in a lower gate–drain capacitance (C_gd) and date–drain charge (Q_gd). Compared with that of conventional SiC trench MOSFET (C-TMOS), the V_F and Q_rr of S-TMOS has reduced by 44% and 75%, respectively, with almost the same forward output current and reverse breakdown voltage. Moreover, the S-TMOS reduces Q_gd and C_gd by 32% and 22%, respectively, in comparison with C-TMOS.

Oversampling sigma–delta (Σ–Δ) analog-to-digital converters (ADCs) are currently one of the most widely used architectures for high-resolution ADCs. The rapid development of integrated circuit manufacturing processes has allowed the realization of a high resolution in exchange for speed. Structurally, the Σ–Δ ADC is divided into two parts: a front-end analog modulator and a back-end digital filter. The performance of the front-end analog modulator has a marked influence on the entire Σ–Δ ADC system. In this paper, a 4-order single-loop switched-capacitor modulator with a CIFB (cascade-of-integrators feed-back) structure is proposed. Based on the chosen modulator architecture, the ASIC circuit is implemented using a chartered 0.35 μm CMOS process with a chip area of 1.72 × 0.75 mm². The chip operates with a 3.3-V power supply and a power dissipation of 22 mW. According to the results, the performance of the designed modulator has been improved compared with a mature industrial chip and the effective number of bits (ENOB) was almost 18-bit.

The defect properties in d-electron containing materials will be strongly influenced by the non-negligible on-site Coulomb interactions. However, this has been omitted in the current widely adopted standard first-principles calculations, such as LDA, leading to a large deviation of calculated results. Therefore, as a comparative case study, in this paper the defects of CdTe are investigated by first-principles calculations including standard LDA and LDA + U, and we find that LDA + U gives more accurate formation energies of the neutral point defects than the standard LDA. The same trend can be found in transition energies of the charged state defects as well. These comparative analyses show that LDA + U gives better results for the defects of CdTe than the standard LDA and requires less computing resource than LAPW, indicating it should have huge potential to model supercells with large number of atoms and strong electron interactions. Moreover, a new anion interstitial defect structure is found to be more stable than the well-known tetrahedron central anion interstitial defect structure \begin{document}${\rm{Te}}_i^a$\end{document}.

Based on the density functional theory, the energy band and electronic structure of β-CuGaO₂ are calculated by the modified Becke-Johnson plus an on-site Coulomb U (MBJ + U) approach in this paper. The calculated results show that the band gap value of β-CuGaO₂ obtained by the MBJ + U approach is close to the experimental value. The calculated results of electronic structure indicate that the main properties of the material are determined by the bond between Cu-3d and O-2p energy levels near the valence band of β-CuGaO₂, while a weak anti-bond combination is formed mainly by the O-2p energy level and Ga-4s energy level near the bottom of the conduction band of β-CuGaO₂. The β-CuGaO₂ thin film is predicted to hold excellent photovoltaic performance by analysis of the spectroscopic limited maximum efficiency (SLME) method. At the same time, the calculated maximum photoelectric conversion efficiency of the ideal CuGaO₂ solar cell is 32.4%. Relevant conclusions can expand β-CuGaO₂ photovoltaic applications.

This paper presents an AOT-controlled (adaptive-on-time, AOT) valley-current-mode buck converter for portable application. The buck converter with synchronous rectifier not only uses valley-current-mode control but also possesses hybrid-mode control functions at the same time. Due to the presence of the zero-current detection circuit, the converter can switch freely between the two operating modes without the need for an external mode selection circuit, which further reduces the design difficulty and chip area. The converter for the application of high power efficiency and wide current range is used to generate the voltage of 0.6–3.0 V with a battery source of 3.3–5.0 V, while the load current range is 0.05–2 A. The circuit can work in continuous conduction mode with constant frequency in high load current range. In addition, a stable output voltage can be obtained with small voltage ripple. In pace with the load current decreases to a critical value, the converter transforms into the discontinuous conduction mode smoothly. As the switching period increases, the switching loss decreases, which can significantly improve the conversion efficiency. The proposed AOT controlled valley current mode buck converter is integrated with standard 0.18 μm process and the simulation results show that the converter provides well-loaded regulations with power efficiency over 95%. When the circuit switches between the two conduction modes drastically, the response time can be controlled within 30 μs. The undershoot voltage is controlled within 25 mV under a large current hopping range.

Type-II superlattice (T2SL) materials are a key element for infrared (IR) detectors. However, it is well known that the characteristics of the detectors with the T2SL layer are greatly affected by the strain developed during the growth process, which determines the performance of IR detectors. Therefore, great efforts have been made to properly control the strain effect and develop relevant analysis methods to evaluate the strain-induced dark current characteristics. In this work, we report the strain-induced dark current characteristics in InAs/GaSb T2SL MWIR photodetector. The overall strain of InAs/GaSb T2SL layer was analyzed by both high-resolution X-ray diffraction (HRXRD) and the dark current measured from the absorber layer at the elevated temperature (≥ 110 K), where the major leakage current component is originated from the reduced minority carrier lifetime in the absorber layer. Our findings indicate that minority carrier lifetime increases as the tensile strain on the InAs/GaSb T2SL is more compensated by the compressive strain through ‘InSb-like’ interface, which reduces the dark current density of the device. Specifically, tensile strain compensated devices exhibited the dark current density of less than 2 × 10^–5 A/cm² at 120 K, which is more than one order of magnitude lower value compared to that of the device without tensile strain relaxation.

Laser photovoltaic devices converting 1064 nm light energy into electric energy present a promising prospect in wireless energy transmission due to the commercial availability of high power 1064 nm lasers with very small divergence. Besides their high conversion efficiency, a high output voltage is also expected in a laser energy transmission system. Meanwhile, 1064 nm InGaAsP multi-junction laser power converters have been developed using p⁺-InGaAs/n⁺-InGaAs tunnel junctions to connect sub-cells in series to obtain a high output voltage. The triple-junction laser power converter structures are grown on p-type InP substrates by metal-organic chemical vapor deposition (MOCVD), and InGaAsP laser power converters are fabricated by conventional photovoltaic device processing. The room-temperature I–V measurements show that the 1 × 1 cm² triple-junction InGaAsP laser power converters demonstrate a conversion efficiency of 32.6% at a power density of 1.1 W/cm², with an open-circuit voltage of 2.16 V and a fill factor of 0.74. In this paper, the characteristics of the laser power converters are analyzed and ways to improve the conversion efficiency are discussed.

Mono-crystalline silicon solar cells with a passivated emitter rear contact (PERC) configuration have attracted extensive attention from both industry and scientific communities. A record efficiency of 24.06% on p-type silicon wafer and mass production efficiency around 22% have been demonstrated, mainly due to its superior rear side passivation. In this work, the PERC solar cells with a p-type silicon wafer were numerically studied in terms of the surface passivation, quality of silicon wafer and metal electrodes. A rational way to achieve a 24% mass-production efficiency was proposed. Free energy loss analyses were adopted to address the loss sources with respect to the limit efficiency of 29%, which provides a guideline for the design and manufacture of a high-efficiency PERC solar cell.

The effects of the quantum well (QW) width, carrier density, and aluminium (Al) concentration in the barrier layers on the optical characteristics of a gallium nitride (GaN)-based QW laser diode are investigated by means of a careful modelling analysis in a wide range of temperatures. The device’s optical gain is calculated by using two different band energy models. The first is based on the simple band-to-band model that accounts for carrier transitions between the first levels of the conduction band and valence band, whereas the second assumes the perturbation theory (k.p model) for considering the valence intersubband transitions and the relative absorption losses in the QW. The results reveal that the optical gain increases with increasing the n-type doping density as well as the Al molar fraction of the Al_xGa_1–xN layers, which originate the GaN compressive-strained QW. In particular, a significant optical gain on the order of 5000 cm^–1 is calculated for a QW width of 40 Å at room temperature. In addition, the laser threshold current density is of few tens of A/cm² at low temperatures.

CMOS technology is one of the most frequently used technologies in the semiconductor industry as it can be successfully integrated with ICs. Every two years the number of MOS transistors doubles because the size of the MOSFET is reduced. Reducing the size of the MOSFET reduces the size of the channel length which causes short channel effects and it increases the leakage current. To reduce the short channel effects new designs and technologies are implemented. Double gate MOSFET design has shown improvement in performance as amplifiers over a single MOSFET. Silicon-based MOSFET design can be used in a harsh environment. It has been used in various applications such as in detecting biomolecules. The increase in number of gates increases the current drive capability of transistors. GAA MOSFET is an example of a quadruple gate around the four sides of channel that increases gate control over the channel region. It also increases effective channel width that improves drain current and reduces leakage current keeping short channel effects under limit. Junctionless MOSFET operates faster and uses less power with increase in ON-state current leading to a good value of I_ON/I_OFF ratio. In this paper, several gate and channel engineered MOSFET structures are analyzed and compared for sub 45 nm technology node. A comparison among different MOSFET structures has been made for subthreshold performance parameters in terms of I_OFF, subthreshold slope and DIBL values. The analog/RF performance is analyzed for transconductance, effective transistor capacitances, stability factor and critical frequency. The paper also covers different applications of advance MOSFET structures in analog/digital or IoT/ biomedical applications.

In this letter, we design and analyze 0.1–1.5 GHz multi-octave quadruple-stacked CMOS power amplifier (PA) in 0.18 μm CMOS technology. By using two-stage quadruple-stacked topology and feedback technology, the proposed PA realizes an ultra-wideband CMOS PA in a small chip area. Wideband impedance matching is achieved with smaller chip dimension. The effects of feedback resistors on the RF performance are also discussed for this stacked-FET PA. The PA shows measured input return loss (< –10.8 dB) and output return loss (< –9.6 dB) in the entire bandwidth. A saturated output power of 22 dBm with maximum 20% power added efficiency (PAE) is also measured with the drain voltage at 5 V. The chip size is 0.44 mm² including all pads.