On Current Limitations in Porous SiC Applications

Abstract

Thermal stability of porous SiC (PSC) with nano-, micro- and double-layer porous structure is assessed through annealing the material at T=900–1700 0C in vacuum and Ar. Changes in composition of PSC under thermal treatment are correlated with porous structure modification. Limitations in PSC technology and applications due to compositional and structure evolution at high temperatures are discussed.

Analysis of Erbium and Vanadium Diffusion in Porous Silicon Carbide

“…Further annealing transformed the "cylinders" into closed voids, with some voids showing tendency to faceting (c). The pattern of porous structure after anneal at 2200 • C for 120 min was similar to that shown in Figure 1(c), as with temperature increasing the modification of porous structure proceeds faster [13]. According to Cheremskoy et al [16], the closing and faceting of the voids confirm that pore modification proceeds according to ripening mechanism, and it is due to vacancy redistribution.…”

“…Vacancies define many physical properties of SiC [7,8], and one of the current subjects of research is their contribution to the formation and properties of porous SiC, a material with many prospective applications [9,10]. The very formation of porous structure in SiC is believed to proceed via vacancy migration and clustering [11], and there are all grounds to believe that experimentally observed modification of the structure under thermal annealing [12,13] is also due to vacancy redistribution. In this respect, diffusion in porous SiC represents a subject of special interest, as pores serve as the sources of vacancies, which should contribute to diffusion.…”

HVPE GaN growth on porous SiC with closed surface porosity

“…It is important that the changes in the pore shape observed in this work after the growth were different from those introduced by thermal treatment [17]. At the same time, the evolution of pores into crack-shaped features, accompanied with the expansion of the dense layer, could be explained on the basis of the known phenomena of pore shape fluctuation and pore healing, which occur in loaded crystalline solids.…”

“…Argon was used as the carrier gas. As was demonstrated recently, PSC is very sensitive to post-anodization treatment involving hightemperature (T ¼ 1200-1700 1C) processing; such treatment may result in degradation of the surface morphology, as well as in graphitization effect [16,17]. To avoid these changes, only the standard surface pretreatment procedure was performed before the growth, which is an exposure of the substrate kept at T ¼ 1000 1C to the argon flow in the HVPE growth machine for a few minutes.…”

Formation of Bare Porous Surface on 6H-SiC Substrates by Photo-Electrochemical Etching

“…On the other hand, it was reported that such vigorous treatments directly affected the quality of porous SiC. 18,19) Therefore, a soft approach is demanded for removing the skin layers. To look for the way, we tried in-situ observation during the PEC etching.…”