Control of metamorphic buffer structure and device performance of In x Ga 1−x As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In 0.5 Ga 0.5 As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique’s precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10 6 cm −2 ), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μ m. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In 0.5 Ga 0.5 As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstruc...

H Q Nguyen, H W Yu, Q H Luc, Y Z Tang, V T H Phan, C H Hsu, E Y Chang and Y C Tseng

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