High-mobility two-dimensional electron gases at AlGaN/GaN heterostructures grown on GaN bulk wafers and GaN template substrates

We report a comparative study of the mobility of two-dimensional electron gases (2DEG) formed at AlGaN/GaN heterostructures by simultaneously growing on substrates with very different dislocation densities. The mobility is seen to depend on the 2DEG charge density directly, but surprisingly, dislocations do not cause a discernible impact on the mobility of the samples within the measured region <25 000 cm 2 V −1 s −1 . This experimental observation questions the generally accepted belief that dislocations are one of the dominant low-temperature scattering mechanisms for low-density 2DEG at AlGaN/GaN structures.