Growth and Characterization of Modulation-DopedAl_xGa_1-xN/GaN Heterostructures

The modulation-doped Al_0.22Ga_0.78N/GaN heterostructures with different Al_0.22Ga_0.78N barrier thicknesses were grown by means of metal--organic chemical vapour deposition. The Al_0.22Ga_0.78N layer still has pseudomorphic growth when its thickness is 53nm. The mobility of the two-dimensional electron gas (2DEG) at the heterointerfaces is much higher than that of the electrons in GaN films at both 300 and 77K. The dramatic decrease of the 2DEG mobility in an Al_0.22Ga_0.78N/GaN heterostructure corresponds to the partial relaxation of the Al_0.22Ga_0.78N barrier.