Dimensionality transformation of the exciton state in quantum wells with asymmetric barriers

摘要

Under the conditions of 2-3D transformation of one-panicle states, the dependence of exciton binding energy E_ex on the well width h has been theoretically studied for quantum structures with barriers of asymmetric height. It is shown that the contribution of one-particle continuous spectrum states to the exciton becomes considerable when the inverse exciton Bohr radius 1/a_b is comparable to the value of wavevector k_c critical for 2-3D transformation. The lack of coincidence between electron and hole k_c values leads to a complicated shape of the E_ex (h) dependence with a minimum at intermediate values of h. The minimum value of E_ex appears to be less than that of the 3D exciton binding energy. The behaviour of the exciton PLE peak position is investigated for an asymmetric structure under the influence of an external electric field.