Possibility for the electrical activation of the carbon antisite by hydrogen inSiC

Abstract

Calculations predict the carbon antisite to be the most abundant intrinsic defect in silicon carbide in a wide range of doping. The isolated carbon antisite is, however, optically and electronically inactive, therefore, difficult to observe by usual experimental techniques. However, ${\mathrm{C}}_{\mathrm{Si}}$ can trap mobile impurities forming electrically active complexes. We will show by ab initio supercell calculations that the hydrogen interstitial is trapped by the carbon antisite forming an electrically active defect which might be detectable by different spectroscopic techniques. The key to activate ${\mathrm{C}}_{\mathrm{Si}}$ by hydrogen is to introduce sufficient amount of hydrogen in the $\mathrm{SiC}$ samples and to avoid formation of vacancies or boron-hydrogen complexes. We have found that the concentration of ${\mathrm{C}}_{\mathrm{Si}}+\mathrm{H}$ complex is above ${10}^{13}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ in highly doped $p$-type chemical vapor deposited (CVD) layers as well as in highly doped $p$-type and $n$-type $\mathrm{SiC}$ samples annealed in high temperature high pressure (HTHP) ${\mathrm{H}}_{2}$ gas. The concentration of ${\mathrm{C}}_{\mathrm{Si}}+\mathrm{H}$ complex can be enhanced in $\mathrm{Al}$-doped CVD and HTHP $\mathrm{SiC}$ samples by applying the appropriate post-annealing temperature. The ${\mathrm{C}}_{\mathrm{Si}}+\mathrm{H}$ complex might be also detected in $\mathrm{Al}$-doped $\mathrm{SiC}$ samples irradiated at room temperature by low energy ${{\mathrm{H}}_{2}}^{+}$ ions.