Influence of nitrogen doping on the properties of 4H–SiC single crystals grown by physical vapor transport

Polytype stability in nitrogen-doped PVT—grown 2″—4H–SiC crystals

“…In the facet area the nitrogen incorporation is increased by a factor between 1.8 and 1.2 compared to the surrounding area for unintentionally and heavily doped crystals, respectively [1]. Furthermore, it was found that after a certain time delay which corresponds to the time between the nitrogen switch off and the first appearance of polytype lamellas the permanent interruption of nitrogen doping was reproducibly correlated to the generation of polytype changes to 15R and/or 6H.…”

“…Furthermore, high nitrogen doping levels can influence the formation of planar defects. At nitrogen concentrations above about 2 Â 10 19 cm À3 the generation of a special type of stacking faults (SFs) observed in 4H-SiC crystals after heat treatment (1100-1200 1C) is drastically enhanced [1][2][3][4][5]. The fault consists of six Si-C bilayers in cubic stacking sequence, can therefore be regarded as a thin 3C lamella and is called double SF.…”

Characterizations and formation mechanism of a new type of defect related to nitrogen doping in SiC crystals

“…We note that the nitrogen concentration in side (7.73 9 10 18 cm -3 ) is much higher than those in other areas. It should be mentioned that high doping of nitrogen (more than 2 9 10 19 cm -3 ) could induce the stacking faults during annealing and polytypic transformation during oxidation [16][17][18][19][20]. But we Fig.…”

“…On top of these, SiC single crystal is attractive for being the substrate in the heteroepitaxial growth of other important materials [5][6][7]. These applications require polytypic stable, large diameter SiC single crystals with low density of defects including micropipes, voids, dislocations, domains and stacking faults [8][9][10][11][12][13][14][15][16][17][18][19]. However, there are still issues need to be addressed in order to meet the increasing demands of high quality in some specific fields of applications.…”

“…It was reported that nitrogen-doped 4H-SiC crystal exhibited extremely low bulk resistivity of 0.0015 X cm [18]. Heavy nitrogen doping, however, could induce stacking faults during annealing [16][17][18][19]. In addition, 4H-3C polytypic transformation during oxidation which is related to high concentration of nitrogen could happen [20].…”