Nearly-free electronlike surface resonance of a β-Si3N4(0001)/Si(111)-8 × 8 interface

R. Flammini,1,* P. Allegrini,2 F. Wiame,3 R. Belkhou,4 F. Ronci,1 S. Colonna,1 D. M. Trucchi,5 F. Filippone,5 S. K. Mahatha,6,7 P. M. Sheverdyaeva,7 and P. Moras7 1CNR-ISM Istituto di Struttura della Materia, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 2CNR-IFN Istituto di Fotonica e Nanotecnologie, Via Cineto Romano 42, I-00156 Roma, Italy 3Institut de Recherche de Chimie Paris (CNRS Chimie ParisTech), Ecole Nationale Superieure de Chimie de Paris (ENSCP), 11 rue Pierre et Marie Curie, F-75005 Paris, France 4Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, B.P. 48F, F-91192 Gif Sur Yvette, France 5CNR-ISM Istituto di Struttura della Materia, Via Salaria km 29.300, I-00019 Monterotondo Scalo (RM), Italy 6International Center for Theoretical Physics (ICTP), I-34014 Trieste, Italy 7CNR-ISM, Istituto di Struttura della Materia, Area Science Park, S.S. 14, km 163.5, I-34149 Trieste, Italy (Received 30 October 2014; revised manuscript received 22 January 2015; published 9 February 2015)