A novel selectively delta-doped AlGaAs/(In,Ga,As)/GaAs pseudomorphic heterostructure

We have investigated the electron density of the delta -doped conventional AlGaAs/GaAs and pseudomorphic AlGaAs/InGaAs/GaAs heterojunctions. Shubnikov -de Hass (SdH) and quantum Hall effect measurements at 4.2 K have been carr ied out to investigate the existence of a quasi-two-dimensional gas (2DEG) in delta Si-doped AlGaAs/GaAs heterostructure. Cases have been also examine d where the g-doping is placed in a narrow quantum well within the AlGaAs b arrier with an Al concentration in the well (x(Al)(well)) less than in the barrier (x(Al)(Barr)). This is intended to increase the electron density. S econdary-ion mass spectroscopy (SIMS) measurements were also performed on o ne of these structures in order to demonstrate the spreading of the dopants . To improve the electron density, we have combined in only one structure t he delta Si, in a narrow quantum well, and the InGaAs layer introduced at t he heterointerface between the AlGaAs and the GaAs. A comparison between th e theoretical and experimental results was performed. The variation trends of calculated electron density are in good agreement with the experimental ones. (C) 2001 Published by Elsevier Science B.V.