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

Photoluminescence (PL) and Zeeman effect measurements in near-infrared lumi nescence bands in Cr-doped 4H and 6H SiC are presented. The PL spectrum con sists of two no-phonon lines (NPLs) at 1.1583 and 1.1898 eV in 4H SiC and t hree NPLs at 1.1556, 1.1797, and 1.1886 eV in 6H SiC. The observed Zeeman s plittings 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 t o 2 with trigonal symmetry and small zero-field splitting values D. In cont rast, the effective g values of the excited state of the center are very an isotropic with g(<parallel to>) in the range of 0.22-0.64 and g(perpendicul ar to) = 0 for different NPLs in both polytypes. Based on the Zeeman result s, the PL is attributed to the internal transition E-1(D)-->(3)A(2)(F) with in the d shell of a substitutional, neutral chromium (Cr4+) in the 3d(2) el ectronic configuration. (C) 1999 American Institute of Physics. [S0021-8979 (99)05520-6].