PHOTOLUMINESCENCE STUDY OF THE INTERFACE IN TYPE-II INALAS-INP HETEROSTRUCTURES

Spatially indirect radiative recombinations (type TI) have been studie d in InAlAs-InP heterostructures grown by gas source molecular beam ep itaxy with emphasis on the direct (InAlAs grown on InP) or inverse (In P on InAlAs) interface composition profile. Based on the results of th eir injection-dependent energy, lifetime and polarization, a new trans ition scheme is proposed: type II transitions have a low injection lim it between 1.27 and 1.28 eV, a long lifetime (tau > 1 mu s) and strong ly shift towards higher energy when increasing the injection. The type II recombination is polarized, the direction of maximum intensity bei ng correlated with the expected interface structure. Lower energy tran sitions (E less than or equal to 1.2 eV) indicate the presence of a we ll transition material at the interface: they should be better labeled as mixed type I-II. Previously published results are also reconsidere d and seem to fit well within this model. (C) 1998 American Institute of Physics. [S0021-8979(98)04916-0].