Angle-dependence of ADF-STEM intensities for chemical analysis of InGaN/GaN.

In this paper we perform angular resolved annular-dark field (ADF) scanning-transmission electron microscopy (STEM) to study the scattered intensity in an InGaN layer buried in GaN as a function of the scattering angle. We achieved angular resolution with a motorized iris aperture in front of the ADF detector. Using this setup, we investigated how the intensities measured in various angular ranges agree with multislice simulations in the frozen-lattice approximation.

Homogeneity and composition of AlInGaN: A multiprobe nanostructure study.

The electronic properties of quaternary AlInGaN devices significantly depend on the homogeneity of the alloy. The identification of compositional fluctuations or verification of random-alloy distribution is hence of grave importance. Here, a comprehensive multiprobe study of composition and compositional homogeneity is presented, investigating AlInGaN layers with indium concentrations ranging from 0 to 17at% and aluminium concentrations between 0 and 39 at% employing high-angle annular dark field scanning electron microscopy (HAADF STEM), energy dispersive X-ray spectroscopy (EDX) and atom probe tomography (APT).