Low-Temperature Static Magnetic Susceptibility of Al0.3Ga0.7As with DX Centers

We have measured the static magnetic susceptibility of Al0.3Ga0.7As doped with 1×1018 cm-3 Te from 20 mK to 1 K in order to study the electron ground state of the DX center. We observed Curie-law temperature dependence of the susceptibility which should come from some paramagnetic centers. The concentration of the paramagnetic center assuming g=2 and spin 1/2 is much lower than that of the DX center. The result indicates that the ground state of the DX center has no spin, thus supporting the negative–U picture of the ground state of the DX center.