Contribution of Dislocations in SiC Seed Crystals on the Melt-Back Process in SiC Solution Growth

Abstract

The melt-back process has a significant effect on the quality of solution-grown SiC crystals. However, the phenomena surrounding the SiC dissolution into the molten alloy during the melt-back process have not been clarified. In this study, the behavior of 4H-SiC dissolution into molten alloy was investigated by using high-temperature in situ observation and subsequent KOH etching, and the effects of different doping conditions and crystal polarity were studied. Local dissolutions with hexagonal pyramid-shape originating from threading screw dislocation (TSD) were observed on the C face of n-type SiC with light nitrogen doping. Our analysis of their behavior revealed that the process was governed by the spiral dissolution. In addition to the dissolution at TSD, local dissolutions at threading-edge dislocations were observed on the Si face of the same crystal. The shape of the local dissolution at the dislocation was significantly affected by the doping conditions and the polarity of the SiC crystal. This local dissolution may occur during the melt-back process, suggesting that it is important to promote the dissolution while maintaining a smooth interface through the selection of the seed crystal and by keeping the degree of interface undersaturation small.

Development of Solid Waste-Based Composite Calcium Ferrite Flux and Its Application in Hot Metal Pre-Dephosphorization

“…Before the experiments, all materials were dried at 110 • C to a constant weight. The melting points of the synthesized fluxes CF-65 and SW-CAF were tested using a high-temperature reaction in situ observation and online analysis system [27,28], as depicted in Figure 2a-c. This system comprises a three-dimensional super-depth-of-field high-temperature video microscope (CCD), a high-temperature microscope for contact angle measurement, and a high-temperature furnace, equipped with the HiTOS observation and control system for real-time in situ video imaging and data recording.…”

Review of solution growth techniques for 4H-SiC single crystal

“…The solvent should be unsaturated with carbon for a slight melt-back of the SiC seed, otherwise, the adhesion of small SiC particles with random crystallographic orientations is formed at the seed surface during the long-time dipping [88] . Kawanishi et al [89] clarified the exponential increase of dissolution rate with interface undersaturation and the various dissolution behaviors for semi-insulating and heavily nitrogendoped crystals. The etching pits originating from dislocations of the damaged layer lead to a rough growth surface.…”

Создание темплейтов для гомоэпитаксиального роста 3C-SiC методом прямого сращивания пластин карбида кремния различающихся политипов

“…В настоящее время процесс взаимодействия карбида кремния с расплавами является предметом интенсивных исследований, но его механизм остается невыясненным. Однако недавно было показано, что на границе раздела твердой и жидкой фаз может происходить растворение ( " травление") поверхности пластин SiC по всей площади контакта, или взаимодействие может носить выраженный селективный характер, когда наиболее интенсивное растворение происходит в местах выхода структурных дефектов на поверхность SiC, граничащую с расплавом [25,26]. Отметим, что различные методы селективного травления (сухого, жидкостного, ex situ и in situ) успешно применяются в ростовых технологиях нитрида галлия с целью достижения эффекта ограничения распространения дефектов, содержащихся в подложках, в эпитаксиальные слои.…”