Le Journal de Physique IV 03 (1993) C5-269-C5-272
Indirect excitons in strained GaxIn1-xAs/InP quantum wellsP. MICHLER, A. HANGLEITER, A. MORITZ, G. FUCHS, V. HÄRLE and F. SCHOLZ
4. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
We present direct experimental evidence that in GaxIn1-xAs/InP quantum wells the bandstructure undergoes a direct-to-indirect gap transition in k-space above a critical value of x. We observe a drastical increase of the measured radiative exciton lifetimes for samples where x>xc, with xc, depending on well width. Using a six-band k.p calculation of the valence subbands we show that for x>xc the valence band maximum is at k ≠ 0, i.e. the bandstructure becomes indirect.
© EDP Sciences 1993