High-Resolution Electron Backscatter Diffraction in III-Nitride Semiconductors

Abstract

The large and increasing interest in III-nitrides semiconductors lies in the wide range of useful applications that can be achieved, from high electron mobility transistors (HEMTs) to light emitting LEDs and lasers. However, the III-nitride materials are usually epitaxially grown on foreign substrates, which lead to the formation of a large number of dislocations and significant strain variations in the epitaxial layers that seriously affect the performance of devices based upon them.

Microscopy of defects in semiconductors

“…Once such sensitivity is achievable it is then possible to calculate the density of dislocations necessary to accommodate the observed misorientations and strain, that is the geometrically necessary dislocations (GNDs) [41]. For an example of what can be achieved with such cross-correlation high resolution electron backscatter diffraction (cross-correlation HR-EBSD), Figure 12(a) shows an EBSD-derived twist map for a patterned epitaxially overgrown GaN thin film [42]. Figure 12(b) shows the distribution of GNDs derived from the measurement of tilt, twist and strain.…”

“…As for ECCI, EBSD has mostly been used to investigate the structural properties of metals and geological materials, however with the development of cross-correlation HR-EBSD, its use for the characterisation of semiconductors is steadily expanding. For example it has been used to study crystal orientation and/or strain in Si [43], Ge [44], SiGe [45] and nitride semiconductors [42,22,46,47]. A detailed description of this technique for the study of InAlN thin films and its correlation with ECCI can be found in [47].…”