TY - JOUR
T1 - Optical phonons in hexagonal AlxInyGa1-x-yN (y ≈ 0.12)
AU - Kasic, A.
AU - Schubert, M.
AU - Off, J.
AU - Scholz, F.
AU - Einfeldt, S.
AU - Hommel, D.
PY - 2002/12
Y1 - 2002/12
N2 - We report on first studies of the phonon mode properties of hexagonal AlxInyGa1-x-yN films. The 200-330 nm thick quaternary films (0 ≤ x ≤ 0.40, y ≈ 0.12), grown by MOCVD on 6H-SiC substrates, are pseudomorphically strained to the GaN buffer layers. We observe and differentiate the influence of strain and alloying on the frequency of the GaN-like E1(TO) phonon mode of AlxInyGa1-x-yN using infrared spectroscopic ellipsometry. Assuming the effective electron mass value of GaN, the free-electron concentrations are estimated from the A1-LO-phonon-plasmon coupled mode frequencies and increase by about two orders of magnitude in going from x = 0 to x = 0.40. We further obtain the composition dependence of the polarity for the AlN-like phonon mode with E1 symmetry. A possibly disorder-induced absorption band occurs above the GaN-like E1(TO) mode.
AB - We report on first studies of the phonon mode properties of hexagonal AlxInyGa1-x-yN films. The 200-330 nm thick quaternary films (0 ≤ x ≤ 0.40, y ≈ 0.12), grown by MOCVD on 6H-SiC substrates, are pseudomorphically strained to the GaN buffer layers. We observe and differentiate the influence of strain and alloying on the frequency of the GaN-like E1(TO) phonon mode of AlxInyGa1-x-yN using infrared spectroscopic ellipsometry. Assuming the effective electron mass value of GaN, the free-electron concentrations are estimated from the A1-LO-phonon-plasmon coupled mode frequencies and increase by about two orders of magnitude in going from x = 0 to x = 0.40. We further obtain the composition dependence of the polarity for the AlN-like phonon mode with E1 symmetry. A possibly disorder-induced absorption band occurs above the GaN-like E1(TO) mode.
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U2 - 10.1002/1521-3951(200212)234:3<970::AID-PSSB970>3.0.CO;2-4
DO - 10.1002/1521-3951(200212)234:3<970::AID-PSSB970>3.0.CO;2-4
M3 - Article
AN - SCOPUS:0036925950
SN - 0370-1972
VL - 234
SP - 970
EP - 974
JO - Physica Status Solidi (B) Basic Research
JF - Physica Status Solidi (B) Basic Research
IS - 3
ER -