Effect of charge distribution in quantum dots array on two-dimensional electron gas

With InGaAs quantum dots (QDs) embedded in the vicinity, GaAs/AlGaAs two-di mensional electron gas (2DEG) was studied by transport measurements and by calculations with QDs charges as Coulomb scattering centers. The mobility o f 2DEG decreases with increasing QDs density up to 5 x 10(10) cm(-2), which can be fitted by considering the finite spatial extension of QD-charge dis tribution. However, two distinct effects are observed as the QDs density in creases from 5 x 10(10) cm(-2) to 2 x 10(11) cm(-2). One is that the 2DEG m obility is saturated at a low level, and the other is that it gradually app roaches the high value of 2DEG without QDs. The former can be reproduced by taking into account the interdot overlapping of electron probability distr ibutions, while the latter is argued to be the result of interdot coupling through wavefunction overlapping. These explanations are supported further by the temperature dependence of the conductance.