Oscillator strength transfer from X to X+ in a CdTe quantum-well microcavity

We report on a study of oscillator strength transfer from the neutral excit on X to the positively charged exciton X+, in a modulation doped CdTe quant um well embedded in a microcavity. The strong-coupling regime between X or X+ and the cavity photon mode has been analyzed for various hole densities p and the oscillator strengths f(X) and f(X+) are derived accurately from p olariton line energies. Far increasing p, f(X) increases and f(X), is shown to decrease linearly with f(X+). We propose a model that accounts far thos e oscillator strength variations. This model relies on an effective cross s ection SX+ = 6.6 X 10(4) Angstrom(2) for the creation of X+ in the vicinity of a hole, and a saturation density equal to 10(11) cm(-2) for phase-space filling effect, [S0163-1829(99)04539-7].