We studied the negative temperature-independent magnetoresistance in a high-density, two-dimensional electron gas in ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}∕\mathrm{GaN}$ heterostructure. This magnetoresistance is attributed to the classical percolation of electrons in a random array of strong scatterers (interface roughness) on the background of the smooth impurity potential. The ratio between the mean free paths due to strong scatterers and smooth disorder was deduced from the comparison of the data and the theory. Independently, the roughness scattering has been measured and calculated using the roughness parameters. Therefore, the negative magnetoresistance in combination with the zero field mobility and Shubnikov–de Haas oscillations analysis allowed us to obtain information about long-range and short-range scattering mechanisms in ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{N}∕\mathrm{GaN}$ heterostructure.

• Received 12 January 2005

DOI:https://doi.org/10.1103/PhysRevB.71.245323