Abstract

Large internal electric fields exist ir strained zincblend-semiconductor quantum wells (QWs) grown along the [111] axis as a result of the piezoelectric effect. These piezoelectric fields shift the interband transition energies to the red¹ and confine the electron and hole wave functions at opposite QW-barrier heterointerfaces. Consequently, photoexcited electron-hole pairs screen the piezoelectric field and shift the transitions to the blue, leading to strong optical nonlinearities. Previous time-resolved studies of the establishment of this blueshift have reported rise times on the order of hundreds of picoseconds, which were attributed to out-of-well screening of the entire multiple quantum well (MQW) region as a result of the escape of the carriers from the individual wells and of the drifting to the ends of the MQW structure.²

© 1996 Optical Society of America