Using 2D integral breadth to study plastic relaxation in a quasi-lattice-matched HgCdTe/CdZnTe heterostructure

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Heterostructures like HgCdTe/CdZnTe are vital for optoelectronic devices.
• Understanding stress and plastic deformation is key to device reliability and performance.
• Traditional methods struggle to quantify complex deformation in layered materials.

Purpose of the Study:

• To investigate stress-induced plastic deformation in HgCdTe/CdZnTe heterostructures using Micro-Laue diffraction.
• To develop and validate a novel 2D integral breadth method for analyzing plastification.
• To determine the elastic limit and plastic onset of the heterostructure components.

Main Methods:

• Utilized Micro-Laue diffraction to obtain cross-section profiles of the heterostructure under induced stress.
• Applied a flexion machine to systematically vary stress levels.
• Introduced and applied a rotationally invariant 2D integral breadth for peak broadening analysis.

Main Results:

• Identified distinct deformation regions within the heterostructure.
• Observed misfit dislocations and depth-dependent peak broadening beyond critical thickness.
• Measured a HgCdTe elastic limit of 15.1 ± 0.7 MPa and noted plastic onset matching the layer's elastic limit.
• Quantified variations in 'plastification easiness' across different regions.

Conclusions:

• The novel 2D integral breadth method accurately assesses critical thickness, plastic onset, and plastification ease.
• Threading dislocation propagation significantly influences plastic deformation onset in the substrate.
• This method is broadly applicable to epitaxial layers with critical thickness exceeding the micro-Laue beam size.