DYNAMICAL STUDIES OF THE RADIATIVE RECOMBINATION PROCESS IN A MODULATION-DOPED GAAS ALGAAS HETEROSTRUCTURE/

We have theoretically and experimentally investigated the dynamics of the radiative recombination process in an n-type modulation doped GaAs /AlGaAs heterostructure. The dynamical reshaping of the potential prof ile across the heterojunction, and the decay of the spatial indirect r adiative recombination between electrons in the two-dimensional electr on gas (2DEG) and photocreated holes in the valence band, has been num erically simulated for various values of the electric field across the heterojunction. The optical matrix elements were deduced from a self- consistent solution of the coupled Schrodinger and Poisson equations a t every discrete point of time in the numerical solution of the rate e quation. The calculated recombination energies and integrated luminesc ence intensities were compared with experimental data from time-resolv ed photoluminescence (PL) measurements on an 800 Angstrom wide GaAs/Al GaAs heterostructure in the time range of 6.2 ns to 1.3 mu s, under va rious applied gate voltages. The theoretical simulations reproduce the experimental observations; a slower radiative decay with increasing p ositive gate voltage and a smaller dynamical red shift of the 2DEG rel ated luminescence with increasing gate voltage. (C) 1998 Elsevier Scie nce B.V. All rights reserved.