Slip systems and misfit dislocations in InGaN epilayers

Abstract

We have studied the microstructure of InGaN layers grown on two different GaN substrates: a standard GaN film on sapphire and an epitaxial lateral overgrown GaN (ELOG) structure. These two materials exhibit two distinct mechanisms of strain relaxation. InGaN epilayers on GaN are typically pseudomorphic and undergo elastic relaxation by the opening of threading dislocations into pyramidal pits. A different behavior occurs in the case of epitaxy on ELOG where, in the absence of threading dislocations, slip occurs with the formation of periodic arrays of misfit dislocations. Potential slip systems responsible for this behavior have been analyzed using the Matthews-Blakeslee model and taking into account the Peierls forces. This letter presents a comprehensive analysis of slip systems in the wurtzite structure and considers the role of threading dislocations in strain relaxation in InGaN alloys.

Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

“…reported as a mechanism of strain relaxation in films with x Շ 0.15, whereas pyramidal slip through the MatthewsBlakeslee mechanism 22 operated when the TD density was significantly reduced. 23,24 When free surfaces intercepted the epitaxial interface, e.g., due to pits, relaxation proceeded through basal slip of misfit dislocation half-loops. 25 Below h cr (according to the People-Bean model), 26 the film retains a principally elastic strain state and the compositional pulling phenomenon appears.…”

Modeling of InGaN/Si tandem cells: comparison between 2-contacts/4-contacts

“…Due to large lattice mismatch between InN and GaN, InGaN a e-mail: walid.elhuni@geeps.centralesupelec.fr grown layer start to relax through dislocation defects after a certain thickness, called critical thickness [9,10]. This critical thickness depends on indium composition to the extend that at 30% of indium the critical thickness is less than 10 nm [11,12].…”

Strain Relaxation via Misfit Dislocation in Step-Graded In GaN Heteroepitaxial Layers Grown on Semipolar (1122) and (1101) GaN

“…Thus they are inactive for MD formation. [10]. Among them the first one shows greater resolve share stress on c-plane and hence most favorable for MD formation.…”

“…Different force experienced by the grown up TD has been calculated in different slip system in InGaN structure which is based on Matthews-Blakeslee balance force model considering the Peierls force [10] [10]- [11]. The misfit force is responsible for generation of MD which depends upon the degree of mismatch.…”