Acceptor levels of the carbon vacancy in $4H$-SiC: combining Laplace deep level transient spectroscopy with density functional modeling

Abstract

We provide direct evidence that the broad Z${}_{1/2}$ peak, commonly observed by conventional DLTS in as-grown and at high concentrations in radiation damaged $4H$-SiC, has two components, namely Z${}_1$ and Z${}_2$, with activation energies for electron emission of 0.59 and 0.67~eV, respectively. We assign these components to ${\mathrm{Z}}_{1/2}^{=}\to {\mathrm{Z}}_{1/2}^{-}+e^{-}\to {\mathrm{Z}}_{1/2}^0+2e^{-}$ transition sequences from negative-$U$ ordered acceptor levels of carbon vacancy (V${}_{\mathrm{C}}$) defects at hexagonal/pseudo-cubic sites, respectively. By employing short filling pulses at lower temperatures, we were able to characterize the first acceptor level of V${}_{\mathrm{C}}$ on both sub-lattice sites. Activation energies for electron emission of 0.48 and 0.41~eV were determined for ${\mathrm{Z}}_1(-/0)$ and ${\mathrm{Z}}_2(-/0)$ transitions, respectively. Based on trap filling kinetics and capture barrier calculations, we investigated the two-step transitions from neutral to doubly negatively charged Z${}_1$ and Z${}_2$. Positions of the first and second acceptor levels of V${}_{\mathrm{C}}$ at both lattice sites, as well as $(=/0)$ occupancy levels were derived from the analysis of the emission and capture data.

References in corpus (2)

• First-principles theory of nonradiative carrier capture via multiphonon emission
• Theory of the carbon vacancy in $4H$-SiC: crystal field and pseudo Jahn-Teller effects

Cited by in corpus (3)

• Silicon carbide diodes for neutron detection
• Characterisation of negative-U defects in semiconductors
• Distinguishing the EH1 and S1 defects in n-type 4H-SiC by Laplace DLTS