THE EXCITONIC STRUCTURE OF ABSORPTION AND MAGNETOABSORPTION SPECTRA NEAR THE TYPE I-II TRANSITION IN STRAINED (IN, GA)AS GAAS HETEROSTRUCTURES/

The absorption and magnetoabsorption of a set of (In, Ga)As/GaAs quant um wells has been studied. The oscillatory structure of magnetoabsorpt ion allows one to reconstruct the energy positions of the Landau level s of the HH1E1 and LH1E1 excitonic states, taking into account the exc iton binding energies calculated variationally. We have found that the potential profile for light holes is nearly flat with small deviation s towards the type II quantum well. Calculation taking account of a co mbined potential for light holes shows that the excitonic transitions associated with the light hole states remain spatially direct in the s ystem under study due to the 'Coulomb well' effect (additional hole co nfinement in the Coulombic potential created by an electron). The osci llator strength of the transitions has been shown to be quite high, wh ich is supported by the data available. Because of a rather high oscil lator strength, one can expect the appearance of a doublet spectral st ructure of light-hole exciton absorption, which was formed by the seco nd light-hole 'oscillatory' states in the combined quantum well potent ial.