Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Nitrides: mostly transport properties and recombination processes

HL 5.3: Vortrag

Montag, 31. März 2014, 10:00–10:15, POT 251

Reduced electron accumulation at InN(0001) surfaces via saturation of surface states by donor- or acceptor-type adsorbates — •Stephanie Reiß, Anja Eisenhardt, Stefan Krischok, and Marcel Himmerlich — Institut für Physik and Institut für Mikro- und Nanotechnologien, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau, Germany

We investigate the impact of selected donor- and acceptor-type adsorbates (potassium and oxygen) on the electronic properties of InN(0001) surfaces implementing in-situ photoelectron spectroscopy. Potassium adsorption leads to a strong decrease in the work function Φ from initially 4.4 to 1.6 eV indicating electron transfer from K adatoms towards the InN surface. In parallel, a reduction of the surface downward band bending V_bb by 0.2 eV and the formation of potassium induced electron states close to the valence band maximum are observed. The interaction of oxygen induces an increase of Φ up to 5.2 eV due to an opposite charge transfer towards the adsorbate and a reduction of V_bb by 0.4 eV. The depletion of the surface electron accumulation layer in both cases can be explained by adsorbate-induced saturation of free dangling bonds at the InN surface resulting in the disappearance of surface states, which initially pin the Fermi level and induce downward band bending. The results prove that the electronic structure can be modified by adlayers resulting in a possible pathway for compensation of the surface electron accumulation.