Photoluminescence studies of 2DEG confinement in InAs ultrathin layer introduced in GaAs/AlGaAs structure

In this work we study the density and confinement effects of 2DEG InAs ultrathin layer introduced in Si-delta-doped GaAs/AlGaAs heterostructures grown by Molecular Beam Epitaxy (MBE) on (1 0 0) oriented GaAs substrates by photoluminescence (PL) measurements. Low temperature PL spectra show the optical transitions (E(e-hh),) and (E(e-lh)) that occur, respectively, between the fundamental states of electrons to heavy holes, and electrons to light holes, in InAs ultrathin layer. The transition energies have been theoretically calculated by solving simultaneously the Schrodinger and Poisson equations within the Hartree approximation. High 2DEG content reveals high photoluminescence efficiency. In fact, the presence of a high density of defects behaves like traps, which can be saturated by the presence of 2DEG in the InAs channel. Photoluminescence measurements as function of the temperature present an S-shape. The evolution of the temperature-dependent integrated PL intensity of the Si-delta-doped structures is governed by two regimes. (C) 2010 Elsevier B.V. All rights reserved.