Optical characterization of bulk mobility in 3C‐SiC films grown on different orientation of Si substrates

Raman microscopy has been used to study the carrier concentration and mobility in n‐doped 3C‐SiC epilayers grown on different silicon substrates, namely (100) Si and (111) Si on axis and off‐axis towards the [110] direction. By analyzing the longitudinal optical phonon‐plasmon coupled mode (LOPC), we were able to estimate the 3C‐SiC electron bulk mobility (μ) within the range between 5 and $500 cm2/Vs.$ The carrier concentration (n) was ranging from $2×1016$ to $6×1018 cm−3.$ The observed trend shows a reduction in the electron mobility as the carrier concentration increases for films grown on any substrate considered, accordingly to the existent theory. For equal values of doping concentration, 3C‐SiC epitaxial films grown on (100) Si substrates show a higher mobility than films grown on (111) Si counterparts. This could be ascribed to a higher defect density in (111) Si samples. A deeper characterization by performing Raman maps shows a broadening and a splitting of the 3C‐SiC transverse optical (TO) peaks for the (111) Si samples, confirming a lower crystal quality than the (100) Si.