Characterization of AlN/AlGaN/GaN:C heterostructures grown on Si(111) using atom probe tomography, secondary ion mass spectrometry, and vertical current-voltage measurements

Complementary studies of atom probe tomography, secondary ion mass spectrometry, and vertical current-voltage measurements are carried out in order to unravel the influence of C-doping of GaN on the vertical leakage current of AlN/AlGaN/GaN:C heterostructures. A systematic increment of the vertical blocking voltage at a given current density is observed in the structures, when moving from the nominally undoped conditions-corresponding to a residual C-background of similar to 10(17) cm(-3) - to a C-content of similar to 10(19) cm(-3) in the GaN layer. The value of the vertical blocking voltage saturates for C concentrations higher than similar to 10(19) cm(-3). Atom probe tomography confirms the homogeneity of the GaN: C layers, demonstrating that there is no clustering at C-concentrations as high as 10(20) cm(-3). It is inferred that the vertical blocking voltage saturation is not likely to be related to C-clustering. (C) 2016 AIP Publishing LLC.