Novel Mn-doped chalcopyrites

Abstract

Heavily Mn-doped II–VI–V₂ semiconductors, such as CdGeP₂ and ZnGeP₂ have been prepared by depositing Mn on single crystalline substrate at nearly 400°C in an ultra high vacuum chamber. Well-defined ferromagnetic hysteresis with a saturation behavior appears in the magnetization curve up to above room temperature. The chemical states of the ZnGeP₂:Mn interface has been clarified by a careful in situ photoemission spectroscopy. The as-prepared surface consists of Ge-rich, metallic Mn compound. In and below the sub-surface region, dilute divalent Mn species as precursors of the DMS phase exist. No MnP phase was observed at any stage of the depth profile. Theoretical band-calculation suggests that the system with vacancies (Cd, V_c, Mn)GeP₂ or a non-stoichiometric (Cd, Ge, Mn)GeP₂ are ferromagnetic and energetically stable although ferromagnetism is not stable in a stoichiometric compound (Cd, Mn)GeP₂.