Polytype stability and defects in differently doped bulk SiC

Polytype inclusions and polytype stability in silicon-carbide crystals

“…The reproducible growth of polytype 4H (in comparison with polytype 6H) is characterized by higher supersaturation [15], by lower temperatures of the process [15][16][17], and requires smaller values of the Si:C ratio in the gas phase [16][17][18]. In particular, stabilization of the growth of the 4H SiC polytype attained using small values of the Si:C ratio in the gas phase [19] is related to a decrease in the effect of the formation of macrosteps (step bunching); this effect will be considered in what follows. Stabilization of the growth of the 4H polytype as a result of an increase in the growth temperature from 2125 to 2327°C [20] is also apparently a consequence of suppression of the effect of macrostep emergence: characteristic values of the growth steps decrease from 10 to 0.25 nm (the last value corresponds to the size of the elementary step, i.e., to the distance between the nearest layers of identical atoms in the direction [0001]).…”

“…At the same time, it is known that doping with nitrogen plays a key role in stabilization of the 4H polytype, i.e., the polytype with a high degree of hexagonality [19,20,23,38]. Furthermore, high concentrations of nitrogen (>10 19 cm -3 ) give rise to the appearance of 4H inclusions in 6H-SiC ingots [38,39].…”

“…Stabilization of the 4H polytype can be related to a number of factors. First, competition with carbon for incorporation into the lattice which leads to enrichment of the growth front with carbon [40]; second, nitrogen is involved in a reaction with carbon forming volatile compounds and increasing carbon transport in the gas phase [41]; third, nitrogen actively prevents three-dimensional growth by decreasing the height of microsteps at the crystallization surface [19]. The mechanism of surface-catalytic action of nitrogen and its effect on layer-by-layer growth was considered by Schulz et al [42].…”

Total pressure‐controlled PVT SiC growth for polytype stability during using 2D nucleation theory

“…Here, we propose a pressure‐controlled growth process for the formation of specific‐stabilized SiC polytypes via PVT. The classical thermodynamic nucleation theory reported by Fissel was used in conjunction with a transient global model reported elsewhere .…”

Thermodynamical analysis of polytype stability during PVT growth of SiC using 2D nucleation theory

“…Several growth parameters such as the growth temperature [5,7], pressure in a furnace [7], supersaturation [8], vapor-phase stoichiometry [5], impurities [9,10] and polarity of seed surface [11,12] have been discussed to influence the polytype stability. Thus, the control of polytype is a complex problem.…”