Silicon Electronics Research Articles

Measurement of Enhanced Spin-Orbit Coupling Strength for Donor-Bound Electron Spins in Silicon.

While traditionally considered a deleterious effect in quantum dot spin qubits, the spin-orbit interaction is recently being revisited as it allows for rapid coherent control by on-chip AC electric fields. For electrons in bulk silicon, spin-orbit coupling (SOC) is intrinsically weak, however, it can be enhanced at surfaces and interfaces, or through atomic placement. Here it is showed that the strength of the spin-orbit coupling can be locally enhanced by more than two orders of magnitude in the manybody wave functions of multi-donor quantum dots compared to a single donor, reaching strengths so far only reported for holes or two-donor system with certain symmetry. These findings may provide a pathway toward all-electrical control of donor-bound spins in silicon using electric dipole spin resonance (EDSR).

Utilizing bypass cement dust in the production of radiation shielding bismuth borate glass

Using the melting-quench technique, a new method for removing bypass cement dust (BCD) was developed in this study using an active environmental glassy system with the chemical formula (65–x)B2O3–5Li2O–5CdO–25BCD–xBi2O3, where x varied from 0 to 30 mol%. A glass density of 3.137 g/cm³ is attained without bismuth, while a density of 5.345 g/cm³ is obtained with 30 mol% Bi2O3. The unit peaks BO3 and BO4 in the FTIR spectra signify the presence of the BLCDBi-series structure. Elevated Bi2O3 concentrations augment BO4 units. Defects influence the optical absorbance of glass within the wavelength range of 190–1000 nm. These defects in the glass network are created by silicon electrons, silicon hole centers, and BCD as well as Bi3+ or Bi6+ after the addition of bismuth oxide to the glassy system. Eg values were found to decrease as Bi2O3 concentration increased, whereas EU and n values exhibited the opposite behavior. A gamma spectroscopy system and the Phy-X/PSD software are used to calculate the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number (Zeff), and effective electron density (Neff) of samples. In addition, the Phy-X/PSD software demonstrated good agreement between experimental and theoretical interpretations. Overall, the results showed that the BLCDBi-30 sample is suitable for use in radiation protection.

Multiple scattering of 855 MeV electrons in amorphous and crystalline silicon: Simulations versus experiment

The angular distribution function of multiple scattering experienced by 855MeV electrons passing through an amorphous silicon plate and an oriented silicon crystal has been studied by means of relativistic molecular dynamics simulations using two types of the potentials that describe electron–atom interaction. The differences in the angular distributions of the beam particles in both media are analyzed. The results obtained are compared to the experimental data and to the results of Monte Carlo simulations.

(Electronics and Photonics Division Poster Award Winner) A High Breakdown Voltage Silicon Carbide (SiC)/Gallium Oxide (Ga2O3) Heterojunction Diode for High Power Applications

Wide and ultrawide bandgap semiconductors demonstrate exceptional performance due to their elevated energy bandgap. This characteristic results in breakdown electric fields surpassing those found in conventional silicon electronics by more than an order of magnitude. Furthermore, the high energy bandgap offers distinctive advantages, including enhanced efficiency, drift velocity, increased voltage blocking, and high-frequency switching, making these semiconductors crucial in pushing the boundaries of electronic technology. Gallium Oxide and Silicon Carbide, distinguished by their unique properties, contribute significantly to the advancement of power electronics. Gallium Oxide, with its wide bandgap of 4.6 – 4.9 eV and excellent thermal stability, stands out for its ability to handle high electric fields and temperatures. Silicon Carbide, on the other hand, boasts a robust combination of high thermal conductivity and a wide bandgap of 3.26 eV, making it well-suited for high-power and high-temperature applications. The combination of these two materials in a heterojunction holds promise for the development of high-performance power devices. In this study, we propose a novel high breakdown voltage Silicon Carbide (SiC)/ Gallium Oxide(Ga2O3) heterojunction diode through TCAD Sentaurus. We present a comparative study of the breakdown voltage and electric field across different heterojunction lengths and under various doping concentrations. The investigated heterojunction showcases a high breakdown voltage of 1899V, making it a promising candidate for advanced power electronics applications. Furthermore, simulation results revealed a significant increase in the breakdown voltage of the SiC/Ga2O3 heterojunction, escalating from 1899 V to 4864 V when extending the heterojunction length. Improved specific ON resistance (RON, sp) and Baliga figure-of-merit (BFOM) will also be presented.

Magneto‐Optical Bi‐Substituted Yttrium and Terbium Iron Garnets for On‐Chip Crystallization via Microheaters

AbstractFerrimagnetic iron garnets enable magnetic and magneto‐optical functionality in silicon photonics and electronics. However, garnets require high‐temperature processing for crystallization which can degrade other devices on the wafer. Here bismuth‐substituted yttrium and terbium iron garnet (Bi‐YIG and Bi‐TbIG) films are demonstrated with good magneto‐optical performance and perpendicular magnetic anisotropy (PMA) crystallized by a microheater built on a Si chip or by rapid thermal annealing. The Bi‐TbIG film crystallizes on Si at 873 K without a seed layer and exhibits good magneto‐optical properties with Faraday rotation (FR) of −1700 deg cm−1. The Bi‐YIG film also crystallizes on Si and fused SiO2 at 873 K without a seed layer. Rapidly cooled films exhibit PMA due to the tensile stress caused by the thermal expansion mismatch with the substrates, increasing the magnetoelastic anisotropy by 4 kJ m−3 versus slow‐cooled films. Annealing in the air for 15 s using the microheater yields fully crystallized Bi‐TbIG on the Si chip.

Comparative analysis of the impact on societies of silicon technology against that of steel

Silicon is one of the most important elements in the world today, and its content in the Earths crust reaches 26%, second only to oxygen. Iron is the fourth most abundant element in the Earths crust, accounting for more than 5% of the Earths mass. It makes up most of the Earths core. Both of them play a vital role in daily human life and economic development. Silicon electronics industry, computer, composite materials, life technology, and other important pillars. Iron is used in construction, manufacturing, transportation, and so on. This article will describe the discovery of two elements and their development history. In addition, this paper analyzes the similarities and differences between the two from different aspects, comparing their impact on society. Finally, this paper gives some prospects for them. The insight gained from this paper can reinforce the understanding of the history of its exploration and their different role in social development.

Anneal-free ultra-low loss silicon nitride integrated photonics

Heterogeneous and monolithic integration of the versatile low-loss silicon nitride platform with low-temperature materials such as silicon electronics and photonics, III–V compound semiconductors, lithium niobate, organics, and glasses has been inhibited by the need for high-temperature annealing as well as the need for different process flows for thin and thick waveguides. New techniques are needed to maintain the state-of-the-art losses, nonlinear properties, and CMOS-compatible processes while enabling this next generation of 3D silicon nitride integration. We report a significant advance in silicon nitride integrated photonics, demonstrating the lowest losses to date for an anneal-free process at a maximum temperature 250 °C, with the same deuterated silane based fabrication flow, for nitride and oxide, for an order of magnitude range in nitride thickness without requiring stress mitigation or polishing. We report record low anneal-free losses for both nitride core and oxide cladding, enabling 1.77 dB m-1 loss and 14.9 million Q for 80 nm nitride core waveguides, more than half an order magnitude lower loss than previously reported sub 300 °C process. For 800 nm-thick nitride, we achieve as good as 8.66 dB m−1 loss and 4.03 million Q, the highest reported Q for a low temperature processed resonator with equivalent device area, with a median of loss and Q of 13.9 dB m−1 and 2.59 million each respectively. We demonstrate laser stabilization with over 4 orders of magnitude frequency noise reduction using a thin nitride reference cavity, and using a thick nitride micro-resonator we demonstrate OPO, over two octave supercontinuum generation, and four-wave mixing and parametric gain with the lowest reported optical parametric oscillation threshold per unit resonator length. These results represent a significant step towards a uniform ultra-low loss silicon nitride homogeneous and heterogeneous platform for both thin and thick waveguides capable of linear and nonlinear photonic circuits and integration with low-temperature materials and processes.

Heterogeneously integrated InGaP/Si waveguides for nonlinear photonics

The heterogeneous integration of III-V semiconductors with the Silicon platform enables the merging of photon sources with Silicon electronics while allowing the use of Silicon mature processing techniques. However, the inherent sufficient quality of III-Vs’ native oxides made imperative the use of deposited interfacial oxide layers or adhesives to permit the bonding. Here we present a novel approach enabling the heterogeneous integration of structured III-V semiconductors on silicates via molecular bonding at 150 °C, much below the CMOS degradation temperature, is presented. The transfer of 235 nm thick and 2 mm long InGaP waveguides with widths of 4.65, 2.6 and 1.22 μm on 4 μm thick Si thermal oxide, with optional SX AR-N 8200.18 cladding, has been experimentally verified. Post-processing of the 1.20 and 0.60 μm input/output tappers has allowed the implementation of double-inverse tapers. The minimal processing requirements and the compatibility with transferring non-cladded structures of the presented technique are demonstrated. The quality of the transferred waveguides bonding interface and their viability for non-linear optics applications has been tested by means of the surface contribution to the optical non-linearity via modal phase-matched second-harmonic generation.

Real-Time Ab Initio Investigation on Hot Electron Relaxation Dynamics in Silicon.

The relaxation of hot electrons in semiconductors is pivotal for both energy harvesting processes and optoelectronics. Utilizing a self-developed non-adiabatic molecular dynamics simulation approach in the momentum space (NAMD_k), we have examined the dynamics of hot electrons in silicon. Whether excited from the Γ or L point, the relaxation dynamics exhibit two distinct stages. Initially, within 100 fs, electrons scatter with phonons throughout the Brillouin zone. Subsequently, over a few picoseconds, they further relax toward the conduction band minimum as a whole. This picture of hot electron relaxation is highly consistent with the quasi-equilibrium hot electron ensemble (HEE) concept. Throughout the hot electron relaxation process, energy transfer to phonons is efficient, leading to time-dependent phonon excitation, which is thoroughly analyzed. This investigation provides a novel perspective on hot electron relaxation in silicon, which holds substantive implications for the realm of photovoltaic and optoelectronic device applications.

Reutilization of Silicon-Cutting Waste via Constructing Multilayer Si@SiO2@C Composites as Anode Materials for Li-Ion Batteries.

The rapid development of the photovoltaic industry has also brought some economic losses and environmental problems due to the waste generated during silicon ingot cutting. This study introduces an effective and facile method to reutilize silicon-cutting waste by constructing a multilayer Si@SiO2@C composite for Li-ion batteries via two-step annealing. The double-layer structure of the resultant composite alleviates the severe volume changes of silicon effectively, and the surrounding slightly graphitic carbon, known for its high conductivity and mechanical strength, tightly envelops the silicon nanoflakes, facilitates ion and electron transport and maintains electrode structural integrity throughout repeated charge/discharge cycles. With an optimization of the carbon content, the initial coulombic efficiency (ICE) was improved from 53% to 84%. The refined Si@SiO2@C anode exhibits outstanding cycling stability (711.4 mAh g-1 after 500 cycles) and rate performance (973.5 mAh g-1 at 2 C). This research presents a direct and cost-efficient strategy for transforming photovoltaic silicon-cutting waste into high-energy-density lithium-ion battery (LIB) anode materials.

Enabling Applications of Electromagnetic Waves at 0.3-1.0 THz Using Silicon Electronic Integrated Circuits.

Over the past 15 years, the output power of silicon submillimeter-wave electronics has increased by a factor greater than 1000 reaching -3.9 dBm at 440 GHz for a single unit in CMOS and -10.7 dBm at 1.01 THz for a 42-element array in SiGe BiCMOS. The smallest power of a 1 kHz bandwidth signal at 420 GHz that can be detected has improved by 100 million times. These and the expected improvements from the ongoing activities should be sufficient to support high resolution imaging with a range of up to several hundred meters, gas sensing up to ∼1 THz, and communication over ∼1000 m. The silicon IC technologies enable integration of complex systems into a small form factor and reduction of manufacturing cost. When broad deployment of submillimeter wave systems for everyday life applications becomes necessary, the silicon IC infrastructure will be the most capable to support the high-volume manufacturing need.

Integrated silicon electron source for high vacuum microelectromechanical system devices

The article presents the process of developing a silicon electron source designed for high-vacuum microelectromechanical system (HV MEMS) devices, i.e., MEMS electron microscope and MEMS x-ray source. Technological constraints and issues of such an electron source are explained. The transition from emitters made of carbon nanotubes to emitters made of pure silicon is described. Overall, the final electron source consists of a silicon tip emitter and a silicon gate electrode integrated on the same glass substrate. The source generates an electron beam without any carbon nanotube coverage. It generates a high and stable electron current and works after the final bonding process of an HV MEMS device.

Epitaxy of wafer-scale single-crystal MoS2 monolayer via buffer layer control

Monolayer molybdenum disulfide (MoS2), an emergent two-dimensional (2D) semiconductor, holds great promise for transcending the fundamental limits of silicon electronics and continue the downscaling of field-effect transistors. To realize its full potential and high-end applications, controlled synthesis of wafer-scale monolayer MoS2 single crystals on general commercial substrates is highly desired yet challenging. Here, we demonstrate the successful epitaxial growth of 2-inch single-crystal MoS2 monolayers on industry-compatible substrates of c-plane sapphire by engineering the formation of a specific interfacial reconstructed layer through the S/MoO3 precursor ratio control. The unidirectional alignment and seamless stitching of MoS2 domains across the entire wafer are demonstrated through cross-dimensional characterizations ranging from atomic- to centimeter-scale. The epitaxial monolayer MoS2 single crystal shows good wafer-scale uniformity and state-of-the-art quality, as evidenced from the ~100% phonon circular dichroism, exciton valley polarization of ~70%, room-temperature mobility of ~140 cm2v−1s−1, and on/off ratio of ~109. Our work provides a simple strategy to produce wafer-scale single-crystal 2D semiconductors on commercial insulator substrates, paving the way towards the further extension of Moore’s law and industrial applications of 2D electronic circuits.

Atomically Precise Manufacturing of Silicon Electronics.

Atomically precise manufacturing (APM) is a key technique that involves the direct control of atoms in order to manufacture products or components of products. It has been developed most successfully using scanning probe methods and has received particular attention for developing atom scale electronics with a focus on silicon-based systems. This review captures the development of silicon atom-based electronics and is divided into several sections that will cover characterization and atom manipulation of silicon surfaces with scanning tunneling microscopy and atomic force microscopy, development of silicon dangling bonds as atomic quantum dots, creation of atom scale devices, and the wiring and packaging of those circuits. The review will also cover the advance of silicon dangling bond logic design and the progress of silicon quantum atomic designer (SiQAD) simulators. Finally, an outlook of APM and silicon atom electronics will be provided.

Low‐Temperature Sputtered Ultralow‐Loss Silicon Nitride for Hybrid Photonic Integration

AbstractSilicon‐nitride‐on‐insulator (Si3N4) photonic circuits have seen tremendous advances in many applications, such as on‐chip frequency combs, Lidar, telecommunications, and spectroscopy. So far, the best film quality has been achieved with low pressure chemical vapor deposition (LPCVD) and high‐temperature annealing (1200°C). However, high processing temperatures pose challenges to the cointegration of Si3N4 with pre‐processed silicon electronic and photonic devices, lithium niobate on insulator (LNOI), and Ge‐on‐Si photodiodes. This limits LPCVD as a front‐end‐of‐line process. Here, ultralow‐loss Si3N4 photonics based on room‐temperature reactive sputtering is demonstrated. Propagation losses as low as 5.4 dB m−1 after 400°C annealing and 3.5 dB m−1 after 800°C annealing are achieved, enabling ring resonators with highest optical quality factors of > 10 million and an average quality factor of 7.5 million. To the best of the knowledge, these are the lowest propagation losses achieved with low temperature Si3N4. This ultralow loss enables the generation of microresonator soliton frequency combs with threshold powers of 1.1 mW. The introduced sputtering process offers full complementary metal oxide semiconductor (CMOS) compatibility with front‐end silicon electronics and photonics. This could enable hybrid 3D integration of low loss waveguides with integrated lasers and lithium niobate on insulator.

Fabrication of a Silicon Electron Multiplier sensor using metal assisted chemical etching and its characterisation

The Silicon Electron Multiplier (SiEM) sensor is a novel sensor concept that enables charge multiplication by high electric fields generated by embedded metal electrodes within the sensor bulk. Metal assisted chemical etching (MacEtch) in gas phase with platinum as a catalyst has been used to fabricate test structures consisting of vertically aligned silicon pillars and strips on top of a silicon bulk. The pillars are around 10µm in height with a diameter of 1.0µm and are arranged as a hexagonal lattice with a pitch of 1.5µm. Electrical characterisations through current–voltage measurements inside a scanning electron microscope and a climate chamber have demonstrated that the MacEtch process is compatible with p–n junctions.

Amorphous silicon intrinsic photomixing detector for optical ranging

Today’s optical range finders or 3D imagers suffer from significant drawbacks and do not allow to combine performance (sensitivity, precision) with simplicity, and scalability enabling very-large scale integration with minimum footprint. Here, we present the amorphous silicon Intrinsic Photomixing Detector (IPD) for direct and highly sensitive optical envelope mixing. The ability to generate a photocurrent that is proportional to the nonlinear mixing of two optical modulation envelope functions enables high performance Time-of-Flight optical ranging at low light levels down to ~0.1mWcm−2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\!0.1\\,{{{{{\\rm{mW}}}}}}{{{{{\\rm{cm}}}}}}^{-2}$$\\end{document} at 444nm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$444\\,{{{{{\\rm{nm}}}}}}$$\\end{document}. The IPD exceeds MHz bandwidth, covers a broad distance detection range from 10cm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10\\,{{{{{\\rm{cm}}}}}}$$\\end{document} to 101m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$101\\,{{{{{\\rm{m}}}}}}$$\\end{document}, and achieves a mean depth resolution below 44mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$44\\,{{{{{\\rm{mm}}}}}}$$\\end{document} for distances up to 25m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$25\\,{{{{{\\rm{m}}}}}}$$\\end{document}. The IPD paves the way towards simple but high-performance photodetectors that allow for very-large scale integration on top of silicon or flexible electronics at low costs with pixel fill factors up to 100%.

Temperature effects on electrical resistivity of selected ceramics for high‐temperature packaging applications

AbstractWe report the results of the characterization of the electrical resistivity of selected ceramic materials, namely aluminum nitride (AlN), silicon nitride (Si₃N₄), beryllium oxide (BeO), yttrium oxide (Y₂O₃), and non‐ceramic silicon dioxide (SiO2), which are candidates for packaging silicon carbide (SiC) sensors and electronics that can operate at temperatures beyond 800°C. Samples of these materials were thermally cycled twice to 1200°C in nitrogen while the bulk and surface resistivities were measured in situ. Although the resistivity values of all samples dropped with increasing temperature, BeO maintained the relatively highest bulk and surface resistivity values at 1200°C of 28 and 34 kΩ cm, respectively, while AlN had the lowest values at 6.8 and 0.64 kΩ cm. In terms of viability for packaging SiC sensors for >800°C operation, AlN and Si₃N₄ are the choice candidates due to their lowest mismatches in the coefficient of thermal expansion with SiC. However, the relative resistivity stability of Si₃N₄ over AlN makes it a promising candidate, even with its lower thermal conductivity relative to AlN.

Ultrasensitive Room Temperature Infrared Photodetection Using a Narrow Bandgap Conjugated Polymer.

Photodetectors operating across the short-, mid-, and long-wave infrared (SWIR-LWIR, λ = 1-14µm) underpin modern science, technology, and society in profound ways. Narrow bandgap semiconductors that form the basis for these devices require complex manufacturing, high costs, cooling, and lack compatibility with silicon electronics, attributes that remain prohibitive for their widespread usage and the development of emerging technologies. Here, a photoconductive detector, fabricated using a solution-processed narrow bandgap conjugated polymer is demonstrated that enables charge carrier generation in the infrared and ultrasensitive SWIR-LWIR photodetection at room temperature. Devices demonstrate an ultralow electronic noise that enables outstanding performance from a simple, monolithic device enabling a high detectivity (D*, the figure of merit for detector sensitivity) >2.44 × 109 Jones (cm Hz1/2 W-1 ) using the ultralow flux of a blackbody that mirrors the background emission of objects. These attributes, ease of fabrication, low dark current characteristics, and highly sensitive operation overcome major limitations inherent within modern narrow-bandgap semiconductors, demonstrate practical utility, and suggest that uncooled detectivities superior to many inorganic devices can be achieved at high operating temperatures.

Lower bound on the spread of valley splitting in Si/SiGe quantum wells induced by atomic rearrangement at the interface

The achievement of universal quantum computing critically relies on scalability. However, ensuring the necessary uniformity for scalable silicon electron spin qubits poses a significant challenge due to the considerable fluctuations in valley splitting energy (E VS) across quantum dot arrays, which impede the initialization of qubit systems comprising multiple spins and give rise to spin–valley entanglement resulting in the loss of spin information. These E VS fluctuations have been attributed to variations in the in-plane averaged alloy concentration along the confinement direction of Si/SiGe quantum wells. In this study, employing atomistic pseudopotential calculations, we unveil a significant spectrum of E VS even in the absence of such concentration fluctuations. This spectrum represents the lower limit of the wide range of E VS observed in numerous Si/SiGe quantum devices. By constructing simplified interface atomic step models, we analytically demonstrate that the lower bound of the E VS spread originates from the in-plane random distribution of Si and Ge atoms within SiGe barriers — an inherent characteristic that has been previously overlooked. Additionally, we propose an interface engineering approach to mitigate the in-plane randomness-induced fluctuations in E VS by inserting a few monolayers of pure Ge barrier at the Si/SiGe interface. Our findings provide valuable insights into the critical role of in-plane randomness in determining E VS in Si/SiGe quantum devices and offer reliable methods to enhance the feasibility of scalable Si-based spin qubits.