In this review paper, several new approaches about the 3C-SiC growth are been presented. In fact, despite the long research activity on 3C-SiC, no devices with good electrical characteristics have been obtained due to the high defect density and high level of stress. To overcome these problems, two different approaches have been used in the last years. From one side, several compliance substrates have been used to try to reduce both the defects and stress, while from another side, the first bulk growth has been performed to try to improve the quality of this material with respect to the heteroepitaxial one. From all these studies, a new understanding of the material defects has been obtained, as well as regarding all the interactions between defects and several growth parameters. This new knowledge will be the basis to solve the main issue of the 3C-SiC growth and reach the goal to obtain a material with low defects and low stress that would allow for realizing devices with extremely interesting characteristics.
Cubic silicon carbide (3C‐SiC) is an emerging material with promising properties for various applications in power electronics, energy saving, and quantum technology. In recent years, size and quality of 3C‐SiC substrates reached a level where real applications become tangible. However, there is still a lack of knowledge concerning defects in 3C‐SiC. Point defects can be considered as one of the key defects, as they influence all applications in one way or another. Herein, the growth rate dependent tailoring of point defects—according to probability and density—is presented for bulk 3C‐SiC grown by epitaxial sublimation growth. Photoluminescence characterization reveals a group of four distinct peaks in the near‐infrared which are assumed to have their joint origin in the carbon vacancy. Moreover, indications for a novel Al‐related defect are presented. The observed defects show bright luminescence in the 175 K/200 K regime and remain excitable up to 300 K.
We investigated the overgrowth of protrusion defects during sublimation growth of cubic silicon carbide (3C-SiC) using freestanding on-axis and off-axis substrates. Three different overgrowth mechanisms were found to contribute to defect elimination: (i) mutual overgrowth by defects of the same type, (ii) real overgrowth by step-flow growth, and (iii) overgrowth by quasi-step-flow growth at surface irregularities. Mechanisms (i) and (iii) are not real overgrowth mechanisms because they are directly linked to the inducing defects themselves or other undesired disturbances of the substrate. However, at high defect densities or for the on-axis substrate, they represent a relevant elimination mechanism. Overgrowth according to (ii) is possible only for off-axis substrates and represents a real elimination mechanism, leading to an improvement of the material quality. In the context of this work, we provide a phenomenological description of the overgrowth principle as well as limitations for the defect elimination, depending on the structure of the protrusions. For the first time, the overgrowth of protrusions has been categorized for different types and qualities of substrates. Fundamental differences were identified, which can lead to a more focused further development of defect elimination in 3C-SiC.
Free standing 3C-SiC wafers with a dimeter of 50 mm and a thickness of ca. 0.8 mm have been grown on a regular base using 3C-SiC CVD seed transfer from Si wafers to a poly-SiC-carrier and a sublimation epitaxy configuration. Up to the thickness of almost 1 mm, stable growth conditions of the cubic polytype have been achieved. The high supersaturation was kept stable by the proper design of the hot zone that enables a high axial temperature gradient at the growth interface. The Sirich gas phase was realized by the application of a Tantalum getter that was integrated into the graphitebased growth cell. Furthermore, an adaption of the growth setup allowed the growth of 3C material with a diameter of 95 mm and bulk material up to 3 mm on 25 mm diameter. Computer simulations were used to determine the supersaturation of the growth setup for different source-to-seed distances. The minimum supersaturation necessary for stable growth of cubic SiC was found to be higher 0.1 for seed already containing the required 3C polytype.
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