Critical thickness of atomically ordered III-V alloys

Journal Article · 11 October 2015 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.4933092 · OSTI ID:1225924

France, Ryan M. ^[1]; McMahon, William E. ^[1]; Guthrey, Harvey L. ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

The critical thickness model is modified with a general boundary energy that describes the change in bulk energy as a dislocation regularly alters the atomic structure of an ordered material. The model is evaluated for dislocations gliding through CuPt-ordered GaInP and GaInAs, where the boundary energy is negative and the boundary is stable. With ordering present, the critical thickness is significantly lowered and remains finite as the mismatch strain approaches zero. The reduction in critical thickness is most significant when the order parameter is greatest and the amount of misfit energy is low. The modified model is experimentally validated for low-misfit GaInP epilayers with varying order parameters using in situ wafer curvature and ex situ cathodoluminescence. With strong ordering, relaxation begins at a lower thickness and occurs at a greater rate, which is consistent with a lower critical thickness and increased glide force. Furthermore, atomic ordering is an important consideration for the stability of lattice-mismatched devices.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1225924
• Report Number(s): NREL/JA-5J00-64874
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 15 Vol. 107; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English