Papers by Keyword: Sublimation Growth

Abstract: It is known that basal plane dislocations (BPDs) and in-grown stacking faults (IGSFs) in the 4H-SiC epitaxial layer cause severe electrical degradation in SiC devices. The impact that sub-surface damage (SSD) on a production-grade 4H-SiC substrate with CMP-finished surface causes on both the BPD propagation and IGSF formation during epitaxial growth was investigated by Dynamic AGE-ing^🄬 (DA). The substrates etched by DA sublimation etching to adjust the residual amount of SSD maintaining a smooth surface without macro step bunching were grown to observe BPD and IGSF density. The obtained results showed that these defect densities decreased exponentially with increasing etching depth. We demonstrated SSD introduced by mechanical processing led BPDs and IGSFs to extend or introduce to the epitaxial layer.

Abstract: One setback that hinders the breakthrough of cubic silicon carbide is the lack of suitable seeding material for sublimation growth methods such as PVT. We present the growth of large area cubic silicon carbide material, up to a diameter of 100 mm, with a sublimation growth process called close spaced PVT (CS-PVT). Freestanding 3C‑SiC seeding layers were grown by a homoepitaxial CVD process. Subsequently CS-PVT was used to grow crystals up to a thickness of 1 mm. To prevent backside sublimation a carbon containing layer was applied as protection. Due to the presence of a wafer bow as well as a rough backside of the used seeds additional effort was necessary to apply the coating. After growth no visible curvature was present independent of the grown layer thickness and sample size. Raman spectroscopy was performed on the seeds and grown crystals, showing that the overall stress level of the material was reduced by CS‑PVT.

Abstract: In recent times, 3C-SiC is gaining more and more interest in terms of applications for optoelectronics and quantum computing. Cubic SiC exhibits a number of luminescent defects in the near infrared originating from deep electronic levels. Temperature dependent photoluminescence measurements were conducted on n-type and p-type 3C-SiC in order to investigate the formation of dopant related point defects as well as intrinsic point defects and defect complexes. The results indicate a number of V_Si, V_C and V_CC_Si related defects which might be suitable candidates for future optoelectronic applications.

Abstract: We report on the growth of bulk 3C-SiC by sublimation on epitaxial seeding layers (3C-SiC/Si) from chemical vapor deposition. We have reached a materials thickness of 0.85 mm and an area of 10.5 cm² which can be enlarged further. The high crystalline quality is characterized by the absence of secondary polytype inclusions and the absence double position grain boundaries.

Abstract: Low resistivity p-type SiC bulk crystals were grown by the sublimation method with using aluminum and nitrogen co-doping. In the sublimation growth of 4H-SiC, to obtain low-resistive p-type crystals are not easy because of the instability of 4H-SiC polytype with highly Al-doping. We have grown < 90 mΩcm p-type 4H-SiC bulk crystals with the co-doping condition. The results of SIMS and Raman spectroscopy show that high concentration of nitrogen co-doping could be effective to the stabilization of 4H polytype with p-type SiC growth.

Abstract: We have investigated the growth of 3C-SiC using sublimation growth in the temperature range from 1800°C to 1950°C. The supersaturation was determined using numerical modeling of the temperature field and gas phase composition by applying quasi-equilibrium thermodynamic conditions. Analysis of the 3C-SiC yield was carried out by optical microscopy, optical absorption, Raman spectroscopy and x-ray analysis. Quantitative data on supersaturation are compared with most stable 3C-SiC nucleation and growth condition. Finally the application to large area growth in a physical vapor transport growth reactor is briefly addressed.

Abstract: In this paper, we present our new setup and technique for obtaining a real-time 3-D volume shape of the SiC crystal using X-ray computed tomography (CT). Hence, it is possible to determine in-situ the shape of the growth interface with high precision at growth temperatures above 2000 °C in a conventional 3" physical vapor transport (PVT) growth system. We show that the size and shape of a facet can be monitored at different stages during growth and furthermore the crystals face boundary can be determined with high precision throughout the whole growth process.

Abstract: Multilayer epitaxial graphene has been grown on the Si-face of 6H-SiC on-axis commercial substrates under high vacuum conditions and at growth temperatures up to 1900 °C, utilizing the standard sublimation growth technique and a modified SiC rapid thermal annealing system which allows for excellent control of heating and cooling ramp rates. The peak growth temperature and total growth time during the graphene growth step, along with the temperature of the initial substrate etch step, were all systematically varied in order to ascertain their effect on the formation of epitaxial graphene films on the SiC surface. Modifying the substrate etch temperature was found to have a significant impact on the morphology of the SiC substrate, with a uniform step structure only developing across the surface within a narrow temperature band. Furthermore, changing the values of the peak temperature or the growth time during the growth step were both shown to have a large effect on the resultant materials properties of the graphene films.

Abstract: In this work a new approach for the production of freestanding cubic silicon carbide (3C SiC) in (001) orientation is presented which is based on the combination of chemical vapor deposition (CVD) and the fast sublimation growth process (FSGP). Fast homoepitaxial growth of 3C SiC using sublimation epitaxy on a template created by CVD growth on silicon substrates allows to obtain thick freestanding material with low defect densities. Using standard silicon wafers as substrate material permits a cost efficient process and the applying of wafers with different orientations. The (001) orientation used in this work will potentially allow further heteroepitaxial growth of other cubic semiconductors, like e.g. gallium nitride (GaN).

Abstract: Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addressed with an emphasis on the enhanced understanding of polytype stability in relation to growth conditions, such as supersaturation and Si/C ratio. It is shown that at low temperature/supersaturation spiral 6H-SiC growth is favored, which prepares the surface for 3C-SiC nucleation. Provided the supersaturation is high enough, 3C-SiC nucleates as two-dimensional islands on terraces of the homoepitaxial 6H-SiC. Effect of different substrate surface preparations is considered. Typical extended defects and their electrical activity is discussed. Finally, possible novel applications are outlined.