Transport properties of two-dimensional electron gas in AlGaAs/GaAs selectively doped heterojunctions with embedded InAs quantum dots

Transport properties of two-dimensional electron gas (2DEG) are studied in selectively doped GaAs/n-AlGaAs heterojunctions, in which nanometer-scale InAs dots are embedded in the vicinity of the GaAs channel. When the distance W _d between the InAs dot layer and the channel is reduced from 80 to 15 nm, the mobility μ of electrons at 77 K decreases drastically from 1.1×10⁵ to 1.1 ×10³ cm²/V s, while the carrier concentration increases from 1.1×10¹¹ to 5.3×10¹¹ cm^-2. Such a reduction of mobility is found only when the average thickness of InAs layer is above the onset level (∼1.5 monolayer) for the dot formation. Origins of these changes in μ and N_s are discussed in connection with dot-induced modulations of the electronic potential V(r) in the channel.