Bulk and epitaxial growth of silicon carbide

Top-seeded solution growth of three-inch-diameter 4H-SiC using convection control technique

Growth rate and surface morphology of 4H–SiC crystals grown from Si–Cr–C and Si–Cr–Al–C solutions under various temperature gradient conditions

Energy savings and efficient usage of electric power are some of the most urgent issues for future sustainable development of human society. Power electronics is recognized as a key technology in this regard, and the innovation of power electronics is increasingly required. The important role of power electronics innovations in the future human society and a technology roadmap of power electronics utilizing wide bandgap semiconductors, which are typically represented by silicon carbide, are presented. This roadmap consists of several different domains in technology, from the materials side to the applications side. On this roadmap, three generations are defined as technological streams. Based on this roadmap, recent progress in silicon carbide power electronics is reviewed, and future prospects are discussed.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/B76BB7C1F95E2A1F3316FF7DCB6A3642/S0883769415000974a.pdf/div-class-title-a-roadmap-for-future-wide-bandgap-semiconductor-power-electronics-div.pdf

A roadmap for future wide bandgap semiconductor power electronics

A long-term growth of high-quality 4H-SiC single crystals by a top-seeded solution growth method using a Si–Cr-based melt was investigated. A new growth technique called “solution growth on concave surface” (SGCS) was developed to help prevent solvent inclusions. The concave shape of the growth surface was achieved by controlling the meniscus height, which enhances the step provision from the periphery to the center. In contrast, under the growth surface, the solution flows from the center to the periphery through convection by inductive heating. The opposite directions of the step flow and solution flow during solution growth create a smooth surface without solvent inclusions. SGCS was used to successfully grow a 1-in. diameter 4H-SiC crystal with a thickness of 30 mm, which is the thickest reported for a solution growth technique, and 1.7-in. diameter high-quality wafers without solvent inclusions were obtained. Schottky barrier diodes were fabricated on 4H-SiC substrates grown by SGCS, which demonstrat...

Solution Growth on Concave Surface of 4H-SiC Crystal

We have grown high-quality long cylindrical (12 mm thick) 4H-SiC bulk crystals by the meniscus formation technique, which was first applied for the solution growth of bulk SiC. It enabled long-term growth by suppressing parasitic reactions such as polycrystal precipitation around the seed crystal. In addition, we could control the growth angle from −22° to 61° by adjusting the meniscus height. The thickness of the grown cylindrical crystals was 12 mm, which is the largest reported until now, and corresponded to a growth rate of 0.6 mm/h. Smooth morphology growth was maintained on the (000-1) C-face. In cross-sectional transmission optical microscopy images, few solvent inclusions and voids were observed. XRD measurements revealed that the FWHM values of the grown crystals were almost the same as those of the seed crystal.

Top-Seeded Solution Growth of 4H-SiC Bulk Crystal Using Si-Cr Based Melt

Crystallinity of 4H-SiC bulk crystal obtained by solution growth technique was characterized mainly by KOH etching of the off-ground and serially ground specimen. Marked reduction of basal plane dislocation, threading edge and screw dislocations during the growth of on-axis crystal was confirmed. Cross-sectional TEM observation revealed the rapid reduction behavior of threading dislocations microscopically. AFM observation of as-grown morphology showed that screw dislocation dipoles is related to the reduction of threading screw dislocations and single domain formation, which is essential for establishing the high crystallinity.

Crystallinity evaluation of 4H-SiC single crystal grown by solution growth technique using Si-Ti-C solution

4H-SiC single crystal with 3-inch diameter was grown by top seeded solution growth (TSSG) technique. We used a new convection control member called “Immersion Guide (IG)” which causes the high and homogenous fluid flow in the solution. As a result, we achieved relatively high growth rate and morphological stability

Growth of large diameter 4H-SiC by TSSG technique

Solution growth on off-axis 4H-SiC sublimation substrate as a buffer layer for the subsequent CVD epitaxial growth was investigated. Dislocation conversion and propagation from the substrate to the CVD epitaxial layer through the solution grown buffer layer was inspected by molten KOH etch pit observation. Effective dislocation conversion from BPD to TED as an effect of the buffer layer insertion with no drastic change in the total EPD was confirmed.

Nobuyuki Yashiro

Papers

Top-Seeded Solution Growth of 4H-SiC Bulk Crystal Using Si-Cr Based Melt

Crystallinity evaluation of 4H-SiC single crystal grown by solution growth technique using Si-Ti-C solution

Growth of large diameter 4H-SiC by TSSG technique

Solution growth of off-axis 4H-SiC for power device application