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- Xie, Mengyao, et al.
(author)
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Effect of Mg doping on the structural and free-charge carrier properties of InN
- 2014
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:16, s. 163504-
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Journal article (peer-reviewed)abstract
- We study the structural and free-charge carrier properties of two sets of InN films grown by molecular beam epitaxy doped with different Mg concentrations from 1x1018 cm-3 to 3.9x1021 cm-3. We determine the effect of Mg doping on surface morphology, lattice parameters, structural characteristics and carrier properties. We show that infrared spectroscopic ellipsometry can be used to evidence successful p-type doping in InN, which is an important issue in InN. High resolution X-ray diffraction, combined with atomic force microscopy measurements reveals a drastic decrease in structural quality of the film for Mg concentrations above 1020 cm-3, accompanied with a significant increase in surface roughness. In addition, a decrease of the c-lattice parameter and an increase of the a-lattice parameter are found with increasing Mg concentration. Different contributions to the strain are discussed and it is suggested that the incorporation of Mg leads to a change of growth mode and generation of tensile growth strain. At high Mg concentrations zinc-blende InN inclusions appear which are suggested to originate from higher densities of stacking faults. Infrared spectroscopic ellipsometry analysis shows a reduced LPP-coupling, manifested as a characteristic dip in the IRSE data, and qualitatively different broadening behavior for Mg concentrations between 1.1x1018 cm−3 and 2.9x1019 cm−3 indicate the existence of a p-type conducting bulk InN layer for these Mg concentrations.
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