Generative Design of Stable Semiconductor Materials Using Deep Learning And DFT

Semiconductor device technology has exceptionally developed in complexity since discovering the bipolar transistor. With the rapid advancement of various technologies, semiconductors with distinct properties are essential. Recently, deep-learning, data-mining, and density functional theory (DFT)- based high-throughput calculations were widely performed to discover potential semiconductors for diverse applications. CubicGAN is a generative adversarial network where high-throughput analyses were done to uncover mechanically and dynamically stable materials with the assistance of DFT. In our work, we screened the semiconductors using a binary classifier from materials found from the CubicGAN. Next, we performed DFT computations to study their thermodynamic stability based on energy-above-hull and formation energy. According to our studies, 12 stable semiconductors were found with a particular class of materials, which we label as AA′MH6. Those are BaNaRhH6, BaSrZnH6, BaCsAlH6, SrTlIrH6, KNaNiH6, NaYRuH6, CsKSiH6, CaScMnH6, YZnMnH6, NaZrMnH6, AgZrMnH6, AgZrMnH6, and ScZnMnH6. It could be shown that AA′MH6 with M=Mn and NaYRuH6 semiconductors have considerably different structural, mechanical, and thermodynamic properties compared to the rest of the AA′MH6 semiconductors. In this study, The maximum bandgap found was approximately 3.3 eV from KNaNiH6, while the minimum bandgap was about 1.3 eV from CaScMnH6. BaNaRhH6, BaCsAlH6, CsKSiH6, KNaNiH6, and NaYRuH6 were identified as wide-bandgap semiconductors, where bandgaps are greater than 2 eV. Furthermore, BaSrZnH6 and KNaNiH6 are a direct bandgap semiconductors, whereas other AA′MH6 semiconductors exhibit indirect bandgaps.

The development of an energy efficient electric drive for agricultural machines

Agriculture is a socially significant sector of the economy. The growth of agricultural production contributes to the stable development of society. It is necessary to use new mechanisms driven by induction motors to increase agricultural productivity. Three-phase induction motors are mainly used in the electric drive of agricultural machines. At the same time, it is advisable to use a single-phase network to supply power to remote farms. In this regard, the development of a single-phase electric drive using three-phase motors becomes relevant. In this work, a study of an original semiconductor device for starting a three-phase induction motor from a single-phase network is made. The simulation model of the device created in the Matlab Simulink environment made it possible to study the electromechanical characteristics of the induction motor when operating from a single-phase network. A comparison of the characteristics of the motor during operation from a three-phase and a single-phase network is carried out. The most significant results of the work are the data obtained that the developed device can be used to start and operate a squirrel cage induction motor from a single-phase network. At the same time, the engine energy parameters change slightly.

Study of GeSn (0.524 eV) Single-Junction Thermophotovoltaic Cells Based on Device Transport Model

Based on the transport equation of the semiconductor device model for 0.524 eV GeSn alloy and the experimental parameters of the material, thermal-electricity conversion performance governed by GeSn diode has been systematically studied in its normal and inverted structure. For the normal p+/n (n+/p) structure, it is demonstrated here that an optimal base doping N d(a) = 3 (7)×1018 cm-3 is observed, and the superior p+/n structure can reach the higher performance. To reduce material consumption, an economical active layer can be comprised of 100-300 nm emitter and 3-6 μm base to attain comparable performance as that for the optimal configuration. The results can offer many useful guidelines for the fabrication of economical GeSn thermophotovoltaic devices.

Automated Measurement and Analysis of Sidewall Roughness (SWR) Using 3D-AFM

As the semiconductor device architecture develops, from planar field-effect transistor (FET) to FinFET and toward gate all around (GAA), it is more needed to measure 3D structure sidewall precisely. Here, we present a 3D-atomic force microscopy (3D-AFM) by Park Systems Corp., a powerful 3D metrology tool to measure SWR of vertical and undercut structures. First, we measured 3 different dies repeatedly to calculate reproducibility in die level. Reproducible results were derived with relative standard deviation under 2%. Second, we measured 13 different dies, including the center and edge of the wafer, to analyze SWR distribution in wafer level and reliable results were measured. And all analysis was performed using a novel algorithm including auto flattening, sidewall detection, and SWR calculation. In addition, SWR automatic analysis software was implemented to reduce analysis time and to provide standard analysis. The result suggests that our 3D-AFM based on tilted Z scanner enabled an advanced methodology for automated 3D measurement and analysis.

EFFECT OF PASSIVATING COATINGS ON METALLIZATION TOPOLOGY IN PRODUCTION OF SEMICONDUCTOR DEVICES

The surface quality of the metallized contact pads on the crystal plays an important role in the production of semiconductor devices. This paper presents experimental studies of the effect of a protective passivation film of silicon oxide on the surface structure of aluminum metallization in the field of forming contact pads. Plasma chemical deposition of passivation layer SiO2 from gas phase (PECVD method) was carried out on prepared samples of silicon with aluminum metallization using a high-frequency power source with a frequency of 13.56 MHz. After that, chemical etching of precipitated silicon oxide was carried out to simulate the process of forming contact areas of semiconductor device crystals. The resistance of the metallization surface to plasma processes was studied by raster electron microscopy. It is shown that as a result of the process cycle, defects of the dislocation type are generated in the applied film Al. The nature of the observed defects has been found to be different. The revealed large square-shaped pits with a size of ~ 1 μm at the places where dislocations come to the surface are of a single nature and appear independently of the processes of applying passivation coatings, which is determined by the orienting action of a single-crystal substrate having some low dislocation density. While the second type of defects, shown by the presence of etching pits measuring ~ 100-300 nm, is characterized by a higher surface density. Moreover, the exclusion of the passivation process with silicon oxide did not lead to the appearance of this type of defects, which determined their nature associated with the ion bombardment of the Al layer during the plasma chemical deposition of silicon oxide from the gas phase. It is also shown that a feature of this type of defects is their disorientation both with respect to the first type of defects and with respect to each other. Detection of the structure of the metallization layers was carried out by X-ray diffraction, the results of which show the polycrystallinity of the formed aluminum metallization. The preferred orientation of the aluminum film corresponds to the substrate Si (111).

Experimental research of the influence of a ferromagnetic core on the speed of an induction-dynamic release with turning anchor type

Circuit breakers for overcurrent protection of semiconductor converters limit the duration and amplitude of the overcurrent at such a level that its thermal effect does not exceed the maximum allowable thermal protection index of the protected semiconductor device. The limitation of the thermal action of the short-circuit current is achieved by reducing the operation time of the circuit breaker. The design of the circuit breaker is changed in such a way that instead of the basic electromagnetic release is used an induction-dynamic release, which consists of an inductor with a ferromagnetic core and a rotary armature in the form of a copper disk. The electrodynamic force producing by the induction-dynamic release for quick operation is determined by the coefficient of mutual inductance of the inductor coil and the armature. Using of a ferromagnetic core entailed an increase in the coefficient of mutual inductance of the coil and armature, therefore, an increase in the electrodynamic force producing by the release, and a decrease in own tripping time of the circuit breaker. On a prototype, an experimental study of the proper operation time of the release was carried out at various values of the electrical parameters of the capacitor bank of the inductor power supply, the winding parameters of the inductor coil and the disk dimensions. The research results have proved both a decrease in the tripping time of the circuit breaker while conserving the energy of the capacitor bank of the inductor, and a decrease in the required energy of the capacitor bank to power the inductor while maintaining the minimum tripping time of the circuit breaker. Reducing the energy of the capacitor bank of the inductor made it possible to reduce the capacity and voltage of the capacitor bank of the supply of the release, and, consequently, its dimensions.

Development of epitaxial PbS layers obtaining method for photoelectric transducers

Photoelectric transducers are a semiconductor device that converts photonic energy into electrical energy. This paper describes obtained by the hotwall epitaxy method epitaxial PbS layers technology. Materials, methods, technological parameters of synthesis were selected and substantiated. A theoretical model of the p-n transition has been developed. The calculation of the main parameters has been done. The hotwall epitaxy method was chosen for the synthesis, because it allows to obtain layers with required properties in a single technological cycle with an economical consumption of material. BaF2 was chosen as the substrate, because in this case a smaller difference in the identity periods and the layer and the substrate thermal expansion coefficients is achieved.

Modeling and Simulations of 4H-SiC/6H-SiC/4H-SiC Single Quantum-Well Light Emitting Diode Using Diffusion Bonding Technique

In the last decade, Silicon carbide (SiC) has emerged as a potential material for high-frequency electronics and optoelectronics applications that may require elevated temperature processing. SiC exists in more than 200 different crystallographic forms, referred to as polytypes. Based on their remarkable physical and electrical characteristics, such as better thermal and electrical conductivities, 3C-SiC, 4H-SiC, and 6H-SiC are considered as the most distinguished polytypes of SiC. In this article, physical device simulation of a light-emitting diode (LED) based on the unique structural configuration of 4H-SiC and 6H-SiC layers has been performed which corresponds to a novel material joining technique, called diffusion welding/bonding. The proposed single quantum well (SQW) edge-emitting SiC-based LED has been simulated using a commercially available semiconductor device simulator, SILVACO TCAD. Moreover, by varying different design parameters, the current-voltage characteristics, luminous power, and power spectral density have been calculated. Our proposed LED device exhibited promising results in terms of luminous power efficiency and external quantum efficiency (EQE). The device numerically achieved a luminous efficiency of 25% and EQE of 16.43%, which is at par performance for a SQW LED. The resultant LED structure can be customized by choosing appropriate materials of varying bandgaps to extract the light emission spectrum in the desired wavelength range. It is anticipated that the physical fabrication of our proposed LED by direct bonding of SiC-SiC wafers will pave the way for the future development of efficient and cost-effective SiC-based LEDs.

Role of Slurry Additives on Chemical Mechanical Planarization of Silicon Dioxide Film in Colloidal Silica Based Slurry

Chemical mechanical planarization (CMP) is a critical process for smoothing and polishing the surfaces of various material layers in semiconductor device fabrication. The applications of silicon dioxide films are shallow trench isolation, an inter-layer dielectric, and emerging technologies such as CMOS Image Sensor. In this study, the effect of various chemical additives on the removal rate of silicon dioxide film using colloidal silica abrasive during CMP was investigated. The polishing results show that the removal rate of silicon dioxide film first increased and then decreased with an increasing concentration of K+, pH, and abrasive size. The removal rate of silicon dioxide film increased linearly as the abrasive concentration increased. The influence mechanisms of various additives on the removal rate of silicon dioxide film were investigated by constructing simple models and scanning electron microscopy. Further, the stable performance of the slurry was achieved due to the COO- chains generated by poly(acrylamide) hydrolysis weaken the attraction between abrasives. High-quality wafer surfaces with low surface roughness were also thus achieved. The desirable and simple ingredient slurry investigated in this study can effectively enhance the planarization performance, for example, material removal rates and wafer surface roughness.