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HL: Halbleiterphysik

HL 2: III-V Halbleiter

HL 2.11: Vortrag

Montag, 24. März 2003, 13:00–13:15, BEY/118

MOVPE Growth of InN Layers and Spectroscopic Ellipsometry Characterization — •Massimo Drago, Torstein Schmidtling, Udo W. Pohl, and Wolfgang Richter — TU-Berlin, Hardenberger Strasse 36 PN 6-I

A value of 0.9 eV has been recently proposed for the band gap of InN, highly contrasting with the former measured values of 1.8-2.1 eV. The difficulty to achieve homogeneous InN layers with good crystal quality plays a major role in the determination of such an important and basic material property. We report on the successful growth of InN layers. Necessary conditions for good layer quality without a foreign buffer layer are a sufficient nitridation of the sapphire substrate, the growth of a low temperature seed layer and the use of in-situ monitoring tools like spectroscopic ellipsometry. Here ellipsometry offers the possibility to find appropriate but extreme growth conditions through displaying the InN electronic properties during growth. Nevertheless the large lattice mismatch with sapphire and the impossibility to anneal the nucleation layer leads to peeling off of parts of the InN layer. The use of a GaN buffer layer improves crystalline quality and allows growth of thicker InN layers. The dielectric function gained from the ellipsometry measurements after growth reveals a band gap value of E0=1 eV at room temperature and higher interband transitions in the range between 4.8 and 6.3 eV.