Precession electron diffraction‐assisted crystal phase mapping of metastable c‐GaN films grown on (001) GaAs

Abstract

The control growth of the cubic meta-stable nitride phase is a challenge because of the crystalline nature of the nitrides to grow in the hexagonal phase, and accurately identifying the phases and crystal orientations in local areas of the nitride semiconductor films is important for device applications. In this study, we obtained phase and orientation maps of a metastable cubic GaN thin film using precession electron diffraction (PED) under scanning mode with a point-to-point 1 nm probe size beam. The phase maps revealed a cubic GaN thin film with hexagonal GaN inclusions of columnar shape. The orientation maps showed that the inclusions have nucleation sites at the cubic GaN {111} facets. Different growth orientations of the inclusions were observed due to the possibility of the hexagonal {0001} plane to grow on any different {111} cubic facet. However, the generation of the hexagonal GaN inclusions is not always due to a 60° rotation of a {111} plane. These findings show the advantage of using PED along with phase and orientation mapping, and the analysis can be extended to differently composed semiconductor thin films.

As4 overpressure effects on the phase purity of cubic GaN layers grown on GaAs substrates by RF-MBE

“…We attribute the origin of these components at stacking faults, since one hexagonal monolayer can be considered as one stacking fault. A discussion about these planar defects in our c-GaN samples was performed by Ruiz-Zepeda et al [20]. Now we want to highlight some characteristics of the c-GaN layers, such as the crystalline quality and cubic phase purity.…”

“…The hexagonal inclusions were found on the {1 1 1} planes, as previously discussed in Fig. 4 and reported by Ruiz-Zepeda et al [20]. The h-GaN component was calculated by comparing the integrated X-ray diffraction intensity of the cubic (0 0 2) and hexagonal (1 01 1) planes, in the same diffraction volume, more details of the calculation procedure can be found in Ref.…”

The Evolution of Growth, Crystal Orientation, and Grain Boundaries Disorientation Distribution in Gold Thin Films

“…This relative new technique utilizes electron diffraction patterns acquired from each section of the sample defined by the step size (spatial resolution up to 1 nm) to obtain crystallographic and structural information of grains and grain boundaries . Different films of metals and semiconductors have been analyzed by PED to study structural changes occurred during annealing and deformation processes, and the relative crystallographic orientation during a film formation …”

Mapping the magnetic and crystal structure in cobalt nanowires

“…The field of view of electron holography and PED-assisted automated crystal orientation mapping (ACOM) in TEM can vary from few nanometers to up to 2 lm. 36,37 The nanowires had diameters of 95 nm 6 5 nm and lengths of 240 nm-5.75 lm for aspect ratios (R ¼ Length/diameter) that varied from 2.5 to 60. The magnetic flux distributions were experimentally observed using off-axis electron holography under zero magnetic field conditions, and phase maps were acquired and employed to distinguish magnetization from individual nanocrystals with high accuracy.…”