Acceptor incorporation in SiC epilayers grown at high growth rate with chloride-based CVD

Abstract

a b s t r a c tA systematic p-type doping study has been performed on 4H-and 6H-silicon carbide (SiC) epilayers grown at high growth rate using chloride-based chemical vapor deposition. The effect of temperature, pressure, growth rate, C/Si-, Cl/Si-ratios and dopant flow on the incorporation of the acceptor atoms aluminum and boron has been studied. The C/Si-ratio on the aluminum incorporation has similar behavior to what has been reported for the standard non-chlorinated low growth rate process, while no clear effect of C/Si-ratio was observed for the boron incorporation. A higher Cl/Si-ratio seems to lead to lower the aluminum and boron incorporation either due to more effective silicon supply at high Cl/Siratio or due to removal of dopant atoms from the surface by chlorine. The doping concentration is stable to the variations in silicon molar fraction, growth pressure and growth temperature for the aluminumdoped layers. Also p-type doping with gallium was tested.

Mechanisms of growth and defect properties of epitaxial SiC

“…The same kind of dependence was shown also in the papers of Pedersen et al, 104,105 where a similar study for the SiH 4 þ HCl process has been conducted for both n and p-type doping. In this study, several different process parameters (growth temperature, growth rate, C/Si, Cl/Si, etc.)…”

Deep levels in iron doped n- and p-type 4H-SiC

“…P-type doping was obtained from the presence of boron (B) in the graphite susceptor and from earlier performed doping studies. 17 The Fe doping was achieved by leaving small metallic flakes of Fe (99.99%) directly on the substrate and in the upstream part of the susceptor. Prior to the metal contact deposition, the samples were chemically cleaned and briefly dipped in hydrofluoric acid to remove the native oxide.…”

Capacitance spectroscopy study of deep levels in Cl-implanted 4H-SiC

“…10 The donor character of Cl and Cl-related complexes 10 can explain why the use of chlorinated precursors does not harm the net-donor concentration 11 but cause the saturation of the net-acceptor concentration. 12 In the following, we present a DLTS study on Climplanted n-or p-type 4H-SiC epilayers, annealed in 100 À 1800 8C temperature range, in order to shed the light on the possible presence of Cl-related electrically active defects in 4H-SiC.…”