Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 53: Nitrides: Preparation of nonpolar and semipolar orientations

HL 53.3: Vortrag

Dienstag, 1. April 2014, 14:30–14:45, POT 151

In-situ analysis of the surface electronic properties of polar and nonpolar InN and GaN films — •Marcel Himmerlich, Anja Eisenhardt, and Stefan Krischok — Institut für Physik and Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau, Germany

Intrinsic surface electronic properties of nitrides are still under debate especially due to a lack of in-situ analyses that allow the characterization of clean surfaces commonly considered in electronic structure calculations. Here we present in-situ studies on the surface properties of polar and nonpolar configurations of GaN and InN thin films prepared by plasma-assisted molecular beam epitaxy utilizing ultraviolet and X-ray photoelectron spectroscopy [1,2]. It will be shown that especially surface reconstructions or relaxations are responsible for the existence of occupied and unoccupied electron states that determine the band alignment at surfaces and interfaces. For both group III nitrides, GaN and InN, the metal-polar surface exhibits different band bending V_bb compared to the N-polar, m-plane and a-plane surface. Thereby V_bb depends on the position of surface states that induce a pinning of the Fermi level. Furthermore, the GaN and InN surface states are easily saturated by adsorbates due to exposure to reactive gases like oxygen or water, partly combined with strong changes in the surface band bending.

[1] M. Himmerlich et al., Phys. Rev. B 88 (2013), 125304.

[2] A. Eisenhardt et al., Appl. Phys. Lett. 102 (2013), 231602.