Doping induced lattice misfit in 4H–SiC homoepitaxy

Experiment on alleviating the bending of CVD-grown heavily Al-doped 4H-SiC epiwafer by codoping of N

“…To understand the reasons why the incorporation of N atoms into Al-doped 4H-SiC leads to the alleviation of wafer bow, we have endeavored to obtain information about the change in the crystal lattice, i.e., the lattice constant change and strain status, through the measurements of reciprocal space mapping from 0008 and 10 18 reflections. The detailed method and calculation are reported by Kallinger et al, 15) Moram and Viker. 30) Figure 3 illustrates the RSM profiles plotted in the Cartesian system using the Q x and Q y coordinates measured from the 0008 reflection on a series of samples A to D grown at various N 2 flow rates and a fixed TMA flow rate.…”

“…These observations suggest that the epilayers are not relaxed but fully strained on the substrate, regardless of the epilayer being Al-doped or Al-N codoped, which coincides with the reported observations. [15][16][17] A numerical analysis of the lattice constant change was carried out using the RSM profiles of the c-lattice constant. The N Al -dependent c-lattice change (mismatch, ¦c/c sub ) is summarized in Fig.…”

“…epiwafer as described in references. 4,6,15) The lattice constant change was deduced from the reciprocal space mapping (RSM) measured on 0008 and 10 18 reflections. The XRD characterization was performed using the incident X-ray beam with the slit sizes of 0.5 © 0.5 and 1 © 1 mm 2 and the angular resolutions (minimal step) of 0.0001 and 0.0002°for the rocking curve and RSM measurements, respectively.…”

Erlangen—An Important Center of Crystal Growth and Epitaxy: Major Scientific Results and Technological Solutions of the Last Four Decades

“…In the frame of her Ph.D. work Birgit Kallinger, who was the last Ph.D. student of Georg Müller, could clarify how the different kinds of dislocations propagate from the substrate into the epilayer. The lattice misfit in the SiC epilayer which is induced by growing a low N or low Al doped layer on a highly N doped substrate was analyzed and the critical epilayer thickness in dependence on the doping concentration was determined . It could be shown that the harmful BPDs can be converted into non‐dangerous threading edge dislocations (TED) during the epi‐process.…”

An experiment on the alleviation of wafer-bending for CVD grown heavily Al-doped 4H-SiC epi-wafer by co-doping of N

“…For high-voltage devices like the insulated gate bipolar transistor (IGBT), a thick Al-doped p + layer with an Al-doping level (N Al ~1×10 19 cm -3 ) is required [1]. Around this N Al range, a direct relation between Al-doping and wafer bow has been reported by Kallinger et al [1,2]. The substitutional Al having a larger covalent radius of 1.25 Å than Si (1.17 Å) was believed to be responsible for the increases of lattice misfit, resulting in a convex wafer bow [2][3][4][5][6].…”