XPS studies on the role of arsenic incorporated into GaN

In this paper physicochemical properties of non-doped GaN0.94As0.06(0001) are presented and compared to the host material. The GaN(As) epitaxial layers were grown by molecular beam epitaxy (MBE) using an As-cracker source and studied in situ in an interconnected analytical chamber using X-ray photoelectron spectroscopy (XPS). The results achieved for the highly ordered (1 x 1), (0001)-oriented GaN(As) samples reveal changes in binding energy (BE) positions of the Ga-3d and N-1s core-level lines compared to the GaN template. These peaks are shifted by about 0.4 eV towards a lower BE and positions of As states correspond to the As-Ga bonds. The valence band (VB) shape of GaN(As) indicates the same features as the host material in the range of higher BEs, however notable changes occur in the vicinity of the Fermi level. The VB maximum of GaN(As) is considerably shifted upwards.