Table 1 Optical and spin properties of V4+ defects in 4H-SiC and 6H-SiC around 3.3 K.

The k1 site is assigned to the 6H-SiC β site on the basis of having the closest crystal configuration and properties to the 4H-SiC β site. k2 is the most cubic-like site and therefore assigned to γ with the smallest GS1-GS2 splitting. The Debye-Waller (DW) factor is a coarse estimation as long-wavelength contributions cannot be observed (see fig. S1). τ is the optical lifetime. The spin parameters (absolute values for the diagonal components xx, yy, and zz) are given in their principal axis with g being the g-factor and A being the hyperfine interaction. xx and yy components are interchangeable, we cannot distinguish gxx from gyy, and a good fit is obtained when Axx and Ayy are equal for GS2 and ES1. θxx, θyy, and θzz are the angles between the principal and the c-axis basis. “-” indicates unresolved parameters.

Site assignmenthkhk1k2
ES1-GS1 (nm)1278.808(6)1335.331(6)1308.592(6)1351.845(6)1387.806(6)
GS2-GS1 (GHz)529(1)43(1)524(1)25(1)16(1)
ES2-ES1 (GHz)181(1)-167(1)628(1)6(1)
ES3-ES2 (GHz)---72(1)-
DW (%)~25~50~45~50~40
τ (ns)167(1)45(1)108(1)11(1)31(1)
GS1: gxx,yy, gzz0*,1.748*0 < g < 1,1.870(5)0*,1.749*-,1.95(2)0 < g < 1,1.933(5)
GS1: Axx, Ayy, Azz (MHz)165,165,232(5)103,188,174(5)165,165,232(5)114,166,171(5)45,215,175(10)
GS2: gxx,yy, gzz-0 < g < 1,2.035(5)--,2.00(2)0 < g < 1,1.972(5)
GS2: Axx,yy, Azz-0,257(5)-0,258(5)0,265(5)
GS2: θxx, θyy, θzz (°)-0,52(2),0-0,50(2),00,51(2),0
ES1: gxx,yy, gzz-,2.24†-,2.03(2)-,2.24*-,2.0(1)-,2.03(2)
ES1: Axx,yy, Azz (MHz)20,220(20)112,52(5)20,200(20)80,20(20)110,50(20)†

* Parameters taken from literature (24, 25).

†Partially resolved parameters obtained by comparison with other sites.