Valence band structure and Mn 3d derived density of states in epitaxially grown zinc-blende MnSe

Abstract

Zinc-blende MnSe films (0–8 monolayers) were grown by molecular-beam epitaxy on ZnSe(100). Angle-resolved photoelectron spectroscopy and resonantly enhanced photoelectron spectroscopy were performed. The experimental valence band structure along Γ-X and Mn 3d-derived partial density of states (Mn 3d PDOS) were determined for the first time. The width of the valence band region was found to be 0.2 eV larger in MnSe than in ZnSe. Emission between 1 and 3.5 eV binding energy (BE) is assigned to MnSe sp-derived bands. The dispersion is weaker than in ZnSe and is related to hybridization with Mn 3d states. Emission between 4 and 5 eV, BE is ascribed to flat Mn 3d-derived bands and to high DOS emission from other regions in the Brillouin zone. Se 3d core emission shifts to 0.6±0.1 eV higher BE as a function of MnSe coverage. By analysis of the Fano-like Mn 3p–3d resonance near hν=50 eV three contributions to the Mn 3d PDOS are derived (denoted M, at 3.4 eV BE, V, at 1.1 eV BE and S, near 7 eV BE, respectively). The relative branching ratios for the latter two features to the first (V/M and S/M) grow monotonically as a function of thin MnSe coverage reaching bulk Zn1−xMnxSe values for thicker films. This behavior is likely due to strain and distortion of the tetrahedral symmetry at the interface.