Improvements of the SiC homoepitaxy process in a horizontal cold-wall CVD reactor

In this research effort, we investigate the influence of the cold-wall reactor geometry on the chemical vapor deposition (CVD) growth process of 4H-SiC and the quality of lightly doped epitaxial layers. Stable growth conditions with respect to growth rate and C/Si ratio of the gas-phase can be achieved by the appropriate choice of the distance between susceptor and walls of the inner quartz tube. A background doping concentration in the range of 10¹⁴ cm⁻³ is realized by employing a high temperature stable and hydrogen etch resistant coating of the graphite susceptor. Doping and thickness homogeneity of epitaxial layers on 35 mm diam. 4H-SiC substrates, expressed by σ/mean, are as low as 6.9 and 7.7%, respectively. From deep level transient spectroscopy measurements, the concentration of the frequently reported intrinsic Z₁-center in 4H-SiC is determined to be below the detection limit of 10¹² cm⁻³.