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Spectroscopic ellipsometry analysis of InGaN/GaN and AlGaN/GaN heterostructures using a parametric dielectric function model

Analyse von InGaN/GaN und AlGaN/GaN Heterostrukturen unter Verwendung eines parametrisierten Models für die dielektrische Funktion
: Wagner, J.; Ramakrishnan, A.; Obloh, H.; Kunzer, M.; Köhler, K.; Johs, B.

Myers, T.H. ; Materials Research Society -MRS-:
GaN and Related Alloys - 1999
Warrendale, Pa.: MRS, 2000 (Materials Research Society symposia proceedings 595)
ISBN: 1-55899-503-X
Symposium GaN and Related Alloys <1999, Boston/Mass.>
Materials Research Society (Fall Meeting) <1999, Boston/Mass.>
Conference Paper
Fraunhofer IAF ()
group III-nitrides; Gruppe III-Nitride; (AlGaIn)N; spectroscopic ellipsometry; spektroskopische Ellipsometrie; dielectric function; dielektrische Funktion

Spectroscopic ellipsometry (SE) has been used for the characterization of ALGaN/GaN and InGaN/GaN heterostructures. The resulting pseudodielectric function spectra were analyzed using a multilayer approach, describing the dielectric functions of the individual layers by a parametric oscillator model. From this analysis, the dielectric function spectra of GaN, Al(x)Ga(1-x)N (x<=0.16), and In(0.13)Ga(0.87)N were deduced. Further, the dependence of the Al(x)Ga(1-x)N band gap energy on the Al mole fraction was derived and compared with photoluminescence data recorded on the same material. The SE band gap data are compatible with a bowing parameter close to 1 eV for the composition dependence of the Al(x)Ga(1-x)N gap energy. Finally, the parametric dielectric functions have been used to model the pseudodielectric function spectrum of a complete GaN/AlGaN/InGaN LED structure.