Identification of molybdenum in 6H-SiC by magnetic resonance techniques.

Abstract

We report on the identification of molybdenum trace impurities in commercial 6H-SiC substrates by conventional and optically detected electron spin resonance (ESR, ODESR) and magnetic circular dichroism (MCD) absorption techniques. The two impurity charge states ${\mathrm{Mo}}^{4+}$ (4${\mathit{d}}^{2}$) and ${\mathrm{Mo}}^{3+}$(4${\mathit{d}}^{3}$) are identified. Consequently, this impurity is electrically active as a deep level acceptor state. In addition we observe the $^{3}$${\mathit{A}}_{2}$${\ensuremath{\rightarrow}}^{3}$${\mathit{T}}_{2}$ crystal field absorptions of ${\mathrm{Mo}}^{4+}$ (4${\mathit{d}}^{2}$) in the spectral range 1.1--1.25 eV. The consequences of the present findings, for the use of Mo as an electrical contact material, are pointed out. \textcopyright{} 1996 The American Physical Society.