Photoluminescence and Zeeman effect in chromium-doped 4H and 6H SiC

Abstract

Photoluminescence (PL) and Zeeman effect measurements in near-infrared luminescence bands in Cr-doped 4H and 6H SiC are presented. The PL spectrum consists of two no-phonon lines (NPLs) at 1.1583 and 1.1898 eV in 4H SiC and three NPLs at 1.1556, 1.1797, and 1.1886 eV in 6H SiC. The observed Zeeman splittings and temperature dependence studies reveal the spin triplet of the ground state and the orbital doublet structure of the excited state of the Cr-related center. All the triplets have almost isotropic g values close to 2 with trigonal symmetry and small zero-field splitting values D. In contrast, the effective g values of the excited state of the center are very anisotropic with $g_{\parallel }$ in the range of 0.22–0.64 and $g_{\perp }\text{=0}$ for different NPLs in both polytypes. Based on the Zeeman results, the PL is attributed to the internal transition ${}^1{\mathrm{E(D)\to }}^3{A}_2\mathrm{(F)}$ within the d shell of a substitutional, neutral chromium $({\mathrm{Cr}}^{\mathrm{4+}})$ in the ${\text{3d}}^2$ electronic configuration.