Le Journal de Physique IV 03 (1993) C5-257-C5-260
Exciton saturation and field screening in InGaAs/InGaAsP multiple quantum wellsT. TÜTKEN, B.J. HAWDON, E. SCHEUBLE, M. ZIMMERMANN, P. KÖNIG, A. HANGLEITER, V. HÄRLE and F. SCHOLZ
4. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 7000 Stuttgart 80, Germany
We performed differential transmission spectroscopy and time resolved pump probe measurements on biased InGaAs/InGaAsP multiple quantum well structures. At low carrier excitation levels we observe a shift in the energy of the excitonic absorption resonance caused by the photogenerated carriers screening the applied electric field within the quantum wells. Increasing the pump power the exciton transmission energy blue shifts until it reaches the zero internal field energy position. For our pump-probe measurements field screening dominates at pump powers lower than 50 W/cm2 while at higher powers exciton saturation becomes dominant. We deduce a saturation intensity of 250 W/cm2.
© EDP Sciences 1993