Two dimensional electron transport in modulation-doped In_0.53Ga_0.47As/AlAs_0.56Sb_0.44 ultrathin quantum wells

We have investigated the growth and electron transport in In_0.53Ga_0.47As/AlAs_0.56Sb_0.44 two dimensional electron gases (2DEG) and compared their properties with In_0.53Ga_0.47As/In_0.52Al_0.48As 2DEGs. For 10 nm thick InGaAs wells, the electron mobility of InGaAs/AlAsSb 2DEGs is comparable to that of InGaAs/InAlAs 2DEGs. Upon thinning the wells to 3 nm, the 2DEG mobility is degraded quickly and stronger interface roughness scattering is observed for InGaAs/AlAsSb heterointerfaces than for InGaAs/InAlAs heterointerfaces. Changing the group-V exposure between As and Sb during growth interruptions at the InGaAs/AlAsSb interfaces did not significantly change the 2DEG mobility. With the insertion of a two monolayer InAlAs at the InGaAs/AlAsSb interfaces, the interface roughness scattering is reduced and the mobility greatly increased. The room temperature 2DEG mobility shows 66% improvement from 1.63 × 10³ cm²/V·s to 2.71 × 10³ cm²/V·s for a 3 nm InGaAs well.