8 March 2014 Point defect management in GaN by Fermi-level control during growth
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Abstract
A point defect control scheme is demonstrated, to control point defects during the growth of doped wide bandgap semiconductors. First the theoretical description of this new concept is presented, second GaN:Mg is used as a model system and as an experimental example to show its feasibility. It can be shown that above bandgap UV-light illumination during the growth can reduce the passivation and compensation of Mg acceptors in GaN:Mg. The amount of hydrogen impurities, that usually passivates Mg at doping concentrations around Mg:2x1019 cm-3, is significantly reduced by UVillumination. The resistivity of samples grown with UV is similar to the resistivity of post-growth annealed samples. No post growth annealing was needed. In contrast samples that are doped below Mg:<1x1018 cm-3 become n-type conductive when the samples are grown with UV illumination. This observation suggests a reduced incorporation of Mg acceptors due to the UV light. At low Mg doping concentrations the native donor incorporation by O donors dominates the conductivity over Mg acceptors. UV-illumination therefore reduces compensation of donors by Mg acceptors. Thus, these observations support the concept of UV illumination as a way to control the Fermi level of different charged point defects to control compensation in doped semiconductors.
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Marc P. Hoffmann, Marc P. Hoffmann, James Tweedie, James Tweedie, Ronny Kirste, Ronny Kirste, Zachary Bryan, Zachary Bryan, Isaac Bryan, Isaac Bryan, Michael Gerhold, Michael Gerhold, Zlatko Sitar, Zlatko Sitar, Ramón Collazo, Ramón Collazo, } "Point defect management in GaN by Fermi-level control during growth", Proc. SPIE 8986, Gallium Nitride Materials and Devices IX, 89860T (8 March 2014); doi: 10.1117/12.2041018; https://doi.org/10.1117/12.2041018
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