Screening effects in modulation-doped quantum wells

The ground bound state of a hydrogenic impurity, screened by the free carriers of a modulation-doped quantum well, is investigated. The dielectric function is calculated at finite temperature in the random-phase approximation and the impurity is located either in the well or in the barrier. Temperature influence on the binding energy is noticeable for low carrier density ($n_e$∼${10}^{11}$/${\mathrm{cm}}^2$) quantum wells. The binding energy of impurities located at the interfaces is strongly temperature dependent because of the screening associated with their own excited carriers.