Optically detected magnetic resonance of excess electrons in type-I quantum wells with a low-density electron gas

Optically detected magnetic resonance is applied to study the fast optical transition processes on a ns time scale with the microwave-induced magnetic transition rate much lower than the optical transition rate. The spin resonance of excess electrons (EESR) is observed with the detection on either the direct exciton or the negatively charged exciton $X^{-}$ emission in type-I ${\mathrm{C}\mathrm{d}\mathrm{T}\mathrm{e}/\mathrm{C}\mathrm{d}}_{1-x}{\mathrm{Mg}}_x\mathrm{Te}$ quantum wells with excess electrons of low density. It is found that the electron-spin-dependent and electron-spin-conserved formation and recombination of $X^{-}$ make the optical detection of EESR feasible.