Si donors in GaN, AlN and their alloys:: A comparison of electron spin resonance experiments and k • p model calculations

Silicon doped wurtzite Al(x)Ga(1)-(x)N alloys with x = 0, 0.15, 0.32, 0.52, 0.75, and 1 were characterized with electron spin resonance experiments. For Al contents x < 0.4 the g-values measured for the shallow Si donor are identical to literature values obtained from nominally undoped material. For x > 0.4 g-values are reported for the first time. The experimental results can be fitted within a five-band k (.) p model in the cubic approximation if a spin orbit splitting of the higher conduction bands of at least 50 meV is considered.