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We have studied the influence of different SiC powder size distributions and the sublimation behavior during physical vapor transport growth of SiC in a 75 mm and 100 mm crystal processing configuration. The evolution of the source material as well as of the crystal growth interface was carried out using in situ 3D X-ray computed tomography (75 mm...
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Context 1
... to the growth process, in situ 2D X-ray imaging [9] was applied to study sublimation behavior in a setup that matches an industrial crystallization tool. Figure 5 shows an optical image of the top of the grown SiC boule which exhibits a predominantly mirror-like surface. Figure 3, the SIKA powder also exhibits a smoother sublimation-recrystallization behavior in the 100 mm SiC growth run than the FAU powder. ...
Context 2
... on the evolution of the growth process shown in Figure 5, the SIKA powder source material exhibits the properties for long term crystal growth runs. There is no visible gap between the crucible wall and the dense disk of the SIKA powder even after 119 h crystal growth while the FAU powder develops such a gap after only 45 h growth time. ...
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Citations
... However, the 200 mm diameter SiC single crystal substrate is still in the early stage of industrialization, and there is still a significant gap in crystal quality and thickness compared to 6-inch SiC. For decades, people have adopted many methods to improve crystal quality and size [8][9][10], including using seed crystals with a certain angle to better meet the requirements of step flow growth mode and reduce the number of defects, using different seed crystal fixation methods to reduce stress caused by different thermal expansion coefficients between materials and graphite [11,12], and adopting different materials and structures to optimize the internal environment of the chamber [13][14][15]. Some researchers studied dislocation formation and found that the largest dislocation density is focused near the graphite and SiC interface [16]. ...
As the size of SiC crystals gradually increase, it becomes increasingly difficult to control the temperature distribution inside the crucible. In this study, numerical simulation tools were used to model the thermal field of SiC single crystal growth using the resistance heating PVT method. Through adjusting the relative position of the heater, adjusting the crucible and insulation structure, and setting up dual heaters, the temperature field distribution patterns under different conditions were obtained. The research results indicate that adjusting the relative positions of the heater, the crucible and insulation structure can achieve uniform temperature conditions under specific conditions. The use of dual heaters can achieve ideal crystal growth conditions with a growth interface temperature difference of less than 10 K, and an axial temperature gradient magnitude of about 10 K/cm, with a smaller edge axial temperature gradient, which is helpful to avoid edge polycrystalline formation and improve crystal quality. Meanwhile, combined with the top insulation layer, more energy-saving effects can be achieved, providing a reference for the preparation of large-sized SiC crystals.
... There are three main technologies that are under research and development. The Physical Vapor Transport (PVT) is the standard industrial process for SiC bulk crystal production in companies in USA, Japan, Germany, Norway, China, Russia [58], however, there are undergoing research for the optimization purposes [59,60]. The crystalline SiC product from Acheson process can be used in powder form as the input to an induction furnace for PVT where bulk crystal grows from sublimation of solid SiC. ...
... Different techniques are employed in preparing SiC materials [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. For the bulk SiC growth, a seeded sublimation or "modified-Lely method" has been commonly used [26][27][28][29][30][31]. ...
... Due to the phase equilibrium in Si and C, the method is based on a physical vapor transportation (PVT) where the source (SiC) in the form of a powder is sublimed at ~ 2300-2500 °C in a closed crucible and deposited on a seed crystal maintained at lower temperature [26]. Breakthrough in the modified-Lely method has enabled the growth of large diameter single high-quality SiC crystals, which resulted in the rapid progress for the epitaxial growth of SiC thin films [19][20][21][22][23][24][25]. ...
... PVT setups are mostly limited to measure the temperatures above and below the growth cell with optical pyrometers through thin channels in the graphite isolation. However, it is possible to utilize 2D X-ray imaging to approximate the in situ growth rate and powder consumption [181][182][183], enabling the fine-tuning of parameters, such as the thermal field and consumption rate of the SiC source. For more specific inquiries of the growth process, advanced 3D imaging can be employed. ...
Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper.
... For the PVT method, increasing the thickness and size of the crystal is the key to reducing the preparation cost, which is also the main direction of researchers [5]. However, unlike the solution method, the gas phase material preparation is faced with lots of difficulties, such as the inability to observe directly, the vast change of raw material state, the deterioration of thermal field conditions during processing and the difficulty in regulating [9][10][11]. Therefore, it is not easy to increase the thickness and maintain high quality simultaneously and the potential of lifting space is limited in a short period of time [12]. ...
As a wide bandgap semiconductor material, silicon carbide has promising prospects for application. However, its commercial production size is currently 6 inches, and the difficulty in preparing larger single crystals increases exponentially with size increasing. Large-size single crystal growth is faced with the enormous problem of radial growth conditions deteriorating. Based on simulation tools, the physical field of 8-inch crystal growth is modeled and studied. By introducing the design of the seed cavity, the radial temperature difference in the seed crystal surface is reduced by 88% from 93 K of a basic scheme to 11 K, and the thermal field conditions with uniform radial temperature and moderate temperature gradient are obtained. Meanwhile, the effects of different processing conditions and relative positions of key structures on the surface temperature and axial temperature gradients of the seed crystals are analyzed in terms of new thermal field design, including induction power, frequency, diameter and height of coils, the distance between raw materials and the seed crystal. Meanwhiles, better process conditions and relative positions under experimental conditions are obtained. Based on the optimized conditions, the thermal field verification under seedless conditions is carried out, discovering that the single crystal deposition rate is 90% of that of polycrystalline deposition under the experimental conditions. Meanwhile, an 8-inch polycrystalline with 9.6 mm uniform deposition was successfully obtained after 120 h crystal growth, whose convexity is reduced from 13 mm to 6.4 mm compared with the original scheme. The results indicate that the optimized conditions can be used for single-crystal growth.
... Due to high requirements for quality substrate in power devices, the growth rate of crystals is slow and the preparation cost is high. For decades, people have employed many methods to improve crystal quality [12][13][14], including using seed crystals with an off-axis angle Materials 2023, 16, 281 2 of 15 to meet the requirements of the step flow growth mode, reducing the number of defects; using different seed crystal fixation methods to reduce the stress caused by the different thermal expansion coefficients of crystal and graphite; and employing different materials and structures to optimize the internal environment of the growth chamber [15][16][17]. Steiner [18] proposed different kinds of nitrogen-doping distribution and seed-mounting strategies. Pezoldt [19] used rapid thermal processing to imprint the polytype transitions by controlling the nucleation and structural evolution during the temperature ramp-up and the steady state. ...
... Therefore, the stability of growth conditions is important, but difficult to maintain, which is also the main constraint against the preparation of large-size and high-quality crystals [16,23]. Considering the high temperature state while crystal grows, the means to regulate the growth conditions are quite limited, including modifying the process parameters of temperature or power, gas pressure, the component ratio, thermal field rotation and thermal field movement [15,24]. Among these, the movement of the thermal field has the most direct effect on growth morphology. ...
SiC substrates have outstanding advantages over traditional materials in power device application, and are mainly prepared by a physical vapor transport method (PVT). Whether the PVT furnace works by resistance heating or induction heating, both face the problem of the deterioration of growth conditions during a long-term process. The relative position of the thermal field directly affects the crystal growth conditions, but the law of specific influence and the change in physical environment inside the thermal field have not been made sufficiently clear and lack systematic research. Therefore, SiC single crystal growth, with different directions and rates in the direction of movement of the heating module, was modeled using a simulation method, and the law of variation of the physical field, including heat flux, temperature, powder porosity and growth rate parameters under different schemes, was analyzed. The study indicates that the decay of raw materials is the primary reason why growth conditions cannot be maintained. The results verified that different coils’ modes of movement have different effects on the improvement or adjustment of SiC crystals’ growth conditions. Under the same temperature control conditions, the coils’ movement rates of 200 μm/h, 0, −200 μm/h and −400 μm/h correspond to the average growth rates of 140, 152, 165 and 172 μm/h, respectively. The results show that downward displacement of the coils is beneficial in compensating for the deterioration of growth conditions, but it is easier to form convex surfaces and is not conducive to expanding diameter growth. This also verifies that the desired crystal growth state can be obtained by adjusting the position of the thermal field.
