000180030 001__ 180030
000180030 005__ 20181203022810.0
000180030 0247_ $$2doi$$a10.1103/PhysRevB.85.245305
000180030 02470 $$2ISI$$a000305089700003
000180030 037__ $$aARTICLE
000180030 245__ $$aGermanium core-level shifts at Ge/GeO2 interfaces through hybrid functionals
000180030 269__ $$a2012
000180030 260__ $$c2012
000180030 336__ $$aJournal Articles
000180030 520__ $$aThe Ge core-level shift across the Ge/GeO2 interface is determined within semilocal and hybrid density functional schemes. We first assess the accuracy achieved within these theoretical frameworks by comparing calculated and measured core-level shifts for a set of Ge-based molecules. The comparison with experimental data results in rms deviations of 0.19 and 0.09 eV for core-level shifts calculated with semilocal and hybrid density functionals, respectively. We also compare calculated core-level shifts at the Ge(001)-c(4 x 2) surface with high-resolution x-ray photoemission spectra finding similar agreement. We then turn to the Ge/GeO2 interface, which we describe with atomistic superlattice models showing alternating layers of Ge and GeO2. The adopted models include a substoichiometric transition region in which all Ge atoms are fourfold coordinated and all O atoms are twofold coordinated, as inferred for Si/SiO2 interfaces. Since the calculation of core-level shifts involves charged systems subject to finite-size effects, we use two different methods to ascertain the core-level shift Delta E-XPS between the oxidation state Ge-0 and Ge+4 across the interface. In the first method, core-hole relaxations are first evaluated in bulk models of the interface components and then complemented by the initial-state shift calculated across the interface, while the second method consists of direct interface calculations corrected through classical electrostatics. Using the more accurate hybrid functional scheme, we obtain a shift Delta E-XPS of 2.7 +/- 0.1 eV. This value is significantly lower than experimental data, which typically fall around 3.3 eV or higher, but the underestimation is consistent with that found for the valence band offset of the same model. This leads to the conclusion that the adopted model structures yield an incorrect description of the interface dipole and emphasizes that Ge/GeO2 interfaces possess different structural properties than their silicon counterparts.
000180030 6531_ $$aPhotoelectron-Spectroscopy
000180030 6531_ $$aSi(100)-Sio2 Interface
000180030 6531_ $$aSi(001)-Sio2 Interface
000180030 6531_ $$a1St Principles
000180030 6531_ $$a1St-Principles
000180030 6531_ $$aSurface
000180030 6531_ $$aSi
000180030 6531_ $$aGe(100)
000180030 6531_ $$aGe(111)
000180030 6531_ $$aModel
000180030 700__ $$0243562$$g185220$$aBinder, Jan Felix
000180030 700__ $$0243561$$g169277$$aBroqvist, Peter
000180030 700__ $$g196801$$aKomsa, Hannu-Pekka$$0243563
000180030 700__ $$aPasquarello, Alfredo$$g109250$$0241891
000180030 773__ $$j85$$tPhysical Review B$$q-
000180030 909C0 $$xU10186$$0252232$$pCSEA
000180030 909CO $$pSB$$particle$$ooai:infoscience.tind.io:180030
000180030 917Z8 $$x109250
000180030 937__ $$aEPFL-ARTICLE-180030
000180030 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000180030 980__ $$aARTICLE