Experimental and theoretical studies on the influence of unintentionally doped carbon on magnetic properties in ZnMnO:N

Mn-N co-doped ZnO film on sapphire substrate is fabricated by metal-organic chemical vapor deposition method with changing the acceptor-doped source and importing the hydrogen and increasing the pressure to suppress carbon (C) approach gradually. X-ray diffraction displays the strong C-axis orientation. Raman sepectrum is employed to analyze vibration modes related to C elements. Hall measurements on the samples by van der Pauw method reveal the transition from n-type to p-type after suppression of C, which is possible due to the complex of (CN)(O) acting as a shallow donor. The first principles simulation calculation for Mn and N codoped ZnO crystals has been perfermed, and the total density of states reveals the strong p-d interaction and magnetic moment existing in the Mn and N codoped ZnO. The introduction of the complex of (CN)(O), causes the p-d interaction to disappear and the magnetic moment to reduce even disappear. Therefore, the formation of magnetic bound polaron of Mn 3d electronics and N 2p local bound electronic determines the magnetic interaction effect, which can be explained from the theoretical predication on the Mn 3d and N 2p ferromagnetic (hole) coupling on the ferromagnetism.