ELECTRONIC PARAMETER AND SUBBAND STRUCTURE VARIATIONS DUE TO AN EMBEDDED AlN POTENTIAL BARRIER LAYER IN Al_0.3Ga_0.7N/GaN HETEROSTRUCTURES

Carrier density of a two-dimensional electron gas (2DEG) in Al 0.3 Ga 0.7 N / GaN and Al 0.3 Ga 0.7 N / AlN / GaN heterostructures was investigated by performing Shubnikov-de Haas (SdH) measurements. The angular-dependent SdH measurements and the fast Fourier transformation results for the SdH data indicated 2DEG occupation of one subband in the triangular potential wells. The carrier densities of the 2DEGs in the Al 0.3 Ga 0.7 N / AlN / GaN and the Al 0.3 Ga 0.7 N / GaN heterostructures at 1.5 K, determined from the SdH data, were 1.28 × 1013 and 1.12 × 1013 cm-2, respectively. The electron carrier density of the 2DEG in the Al 0.3 Ga 0.7 N / GaN heterostructure with an AlN embedded potential barrier layer was larger than that in the Al 0.3 Ga 0.7 N / GaN heterostructure. The electronic subband energies, the wave functions, and the Fermi energies in the Al 0.3 Ga 0.7 N / AlN / GaN and Al 0.3 Ga 0.7 N / GaN heterostructures were calculated by using a self-consistent method taking into account spontaneous and piezoelectric polarizations.