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- Kasic, A., et al.
(författare)
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Phonons and free-carrier properties of binary, ternary, and quaternary group-III nitride layers measured by infrared Spectroscopic Ellipsometry
- 2003
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; 0:6 SPEC. ISS., s. 1750-1769
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work reviews recent ellipsometric investigations of the infrared dielectric functions of binary, ternary, and quaternary group-III nitride films. Spectroscopic Ellipsometry in the mid-infrared range is employed for the first time to determine phonon and free-carrier properties of individual group-III nitride heterostructure components, including layers of some ten nanometer thickness. Assuming the effective carrier mass, the free-carrier concentration and mobility parameters can be quantified upon model analysis of the infrared dielectric function. In combination with Hall-effect measurements, the effective carrier masses for wurtzite n- and p-type GaN and n-type InN are obtained. The mode behavior of both the E1(TO) and A1(LO) phonons are determined for ternary compounds. For strain-sensitive phonon modes, the composition and strain dependences of the phonon frequencies are differentiated and quantified. Information on the crystal quality and compositional homogeneity of the films can be extracted from the phonon mode broadening parameters. A comprehensive IR dielectric function database of group-III nitride materials has been established and can be used for the analysis of complex thin-film heterostructures designed for optoelectronic device applications. Information on concentration and mobility of free carriers, thickness, alloy composition, average strain state, and crystal quality of individual sample constituents can be derived. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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- Soderstrom, D., et al.
(författare)
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Dopant diffusion and current-voltage studies on epitaxial InP codoped with Ru and Fe
- 2001
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Ingår i: Journal of Electronic Materials. - 0361-5235 .- 1543-186X. ; 30:8, s. 972-976
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Tidskriftsartikel (refereegranskat)abstract
- Semi-insulating Fe and Ru codoped InP epitaxial layers grown by low-pressure hydride vapor phase epitaxy have been investigated. InP:Ru and InP:Fe,Ru layers were grown on p-InP:Zn and n-InP:S substrates, in order to study dopant diffusion and electrical characteristics. Dopant diffusion profiles of Ru, Fe and Zn were measured by secondary ion mass spectroscopy. A small but noteworthy diffusion front is observed when InP:Ru is adjacent to InP:Zn, but not when adjacent to n-InP. For InP:Fe codoped with Ru a pronounced interdiffusion of Fe and Zn is observed for Ru concentrations less than 2 X 10(17) cm(-3), but, for a higher Ru concentration the interdiffusion is clearly suppressed. Moreover, when InP is codoped with Fe and Ru, the small diffusion tail of Ru in InP:Zn vanishes. Unlike InP:Fe, resistivities above 1 X 10(8) Ohm cm are measured for both electron and hole-current injection in InP:Fe,Ru.
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- Soderstrom, D., et al.
(författare)
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Electrical characterization of ruthenium-doped InP grown by low pressure hydride vapor phase epitaxy
- 2001
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Ingår i: Electrochemical and solid-state letters. - 1099-0062 .- 1944-8775. ; 4:6, s. G53-G55
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of ruthenium-doped InP grown by low-pressure hydride vapor phase epitaxy have been studied. Current voltage measurements were conducted at temperatures between 20 and 200 degreesC for samples doped with Ru in the range 1 x 10(17) to 5 X 10(17) cm(-3). In this doping range, the specific resistivity of n(+)/InP:Ru/n(+) structures accommodating electron injection is less than or equal to1 x 10(4) Ohm cm and that of p(+)/InP:Ru/p(+) structures accommodating hole injection is as high as 3 x 10(10) Ohm cm. The reason for such a huge difference in the resistivity of these structures is attributed to a low activation of deep Ru acceptors, thus rather giving rise to an n(-) layer than a semi-insulating layer, as supported by our theoretical simulation. Analysis of the Arrhenius plots constructed from the temperature-dependent I-V curves yield an average activation energy of Ru with reference to the conduction band equal to 0.44 and 0.52 eV under electron and hole injection, respectively.
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- Soderstrom, D., et al.
(författare)
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Studies on ruthenium-doped InP growth by low-pressure hydride vapor-phase epitaxy
- 2001
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 148:7, s. G375-G378
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Tidskriftsartikel (refereegranskat)abstract
- Ruthenium-doped InP (InP:Ru) has been grown by low-pressure hydride vapor-phase epitaxy (LP-HVPE) using bis(eta (5)-2,4-dimethylpentadienyl)ruthenium(II) as precursor. Ruthenium concentrations in the range 2 x 10(15) to 2 x 10(18) cm(-3) have been achieved. The Ru incorporation has been studied in terms of incorporation flux, and it is shown that the growth rate limits: the incorporation rate. From current-voltage measurements on n-InP/InP:Ru/n-InP and p-InP/InP:Ru/p-InP structures, resistivities greater than 10(3) Omega cm and greater than 10(10) Omega cm have been obtained, respectively.
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