We have studied electronic and structural characterizations of high indium content metamorphic InGaAs/InAlAs modulation-doped heterostructures. An improved low-temperature electron mobility of mu (e) = 5.45 x 10(5) cm(2) Vs in [(1) over bar 1 0] was confirmed for a directed Hall-bar sample when Si-doped InAlAs layer was slightly etched. In addition, inplane mobility anisotropy of 40% between [(1) over bar 1 0] and [1 1 0] directions. We confirmed. This anisotropy seems to br originated fi om the different undulation period between[(1) over bar 1 0] and [1 1 0] directions. We theoretically calculated electron mobility taking both alloy disorder scattering and background impurity scattering into account. It is found that the calculated and experimental values are in good agreement.