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A pinboard by
Ganesh Iyer
PINBOARD SUMMARY

A novel FE algorithm is developed to simulate stress state of an HEMT device arising due to defects

In hetero-epitaxial systems interface effects gain prominence and the interplay of stress and defects determines the evolution of the system. During epitaxial growth the coherency stresses can be relaxed due to multiple mechanisms, which include: (i) the formation of a misfit interfacial edge dislocations, (ii) interfacial cracks and (iii) surface cracks. In the current work, the critical sizes for the occurrence of these phenomena are determined from finite element simulations, via global energy criteria and local stress concentration effects. GaN/AlGaN and GeSi/Si systems are used as model systems for the computations. An interesting scenario, which combines epitaxy and phase transformation, is the case of precipitation in epitaxial films. A complex interaction exists between the multiple sources of stresses and the evolution of the system with growth. Keeping the abovementioned effects in view, the finite element methodology is extended to study the effect of geometry on critical thickness of epitaxial stripes, and stress state of multilayer devices