The interface between III–V and gate dielectrics is a key challenge in developing high performance III–V MOSFETs such as GaAs and InGaAs. The high density of interface states (Dit) makes it very difficult to modulate surface Fermi level and inversion carrier concentration. By growing an epitaxial layer (ALE) of La2O3 dielectric on GaAs(111)A, Dit can be effectively reduced and Fermi levels movement efficiency is greatly improved. In this paper, we studied systematically the carrier transport including IV, CV and conductance method at temperatures ranging from 300 K to low temperatures down to 4.3 K.