Nanoscale mapping of the full strain tensor, rotation and composition in partially relaxed In$_x$Ga$_{1-x}$N layers by scanning X-ray diffraction microscopy

TL;DR

This paper introduces a non-destructive scanning X-ray diffraction microscopy method to map the full strain tensor, rotation, and composition in partially relaxed InGaN layers, aiding in understanding strain effects in semiconductor devices.

Contribution

The work develops a formalism to extract all components of strain and orientation from scanning X-ray diffraction data, enabling detailed microscopic analysis of strain relaxation and composition in InGaN layers.

Findings

Successfully mapped the full strain tensor and lattice orientation.

Separated effects of indium content variation and dislocations.

Provided insights into strain relaxation mechanisms.

Abstract

Strain and composition play a fundamental role in semiconductor physics, since they are means to tune the electronic and optical properties of a material and hence develop new devices. Today it is still a challenge to measure strain in epitaxial systems in a non-destructive manner which becomes especially important in strain-engineered devices that often are subjected to intense stress. In this work, we demonstrate a microscopic mapping of the full tensors of strain and lattice orientation by means of scanning X-ray diffraction microscopy. We develope a formalism to extract all components of strain and orientation from a set of scanning diffraction measurements and apply the technique to a patterned In$_x$Ga$_{1-x}$N double layer to study strain relaxation and indium incorporation phenomena. The contributions due to varying indium content and threading dislocations are separated and analyzed.