Effect of the magnetic order on the room-temperature band-gap of Mn-doped ZnO thin films

Abstract

Exchange interaction between localized magnetic moments mediated by free charge carriers is responsible for a non-monotonic dependence of the low-temperature energy band-gap in dilute magnetic semiconductors. We found that in weakly doped Mn-ZnO films, increasing the exchange interaction by increasing the concentration of free charge carriers results in a red-shift of the nearband-edge emission peak at room temperature. An increase of Mn concentration widens the band gap, and a blue-shift prevails. Exchange interaction can be used to tune the room-temperature optical properties of the wide-band gap semiconductor ZnO. V

Correlation between oxygen vacancies and dopant concentration in Mn-doped ZnO nanoparticles synthesized by co-precipitation technique

“…Mukherjee et al took the attitude that the observed RTFM in Mn-doped ZnO nanocrystalline M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT powders synthesized by a wet chemical method could be attributed to the substitutional incorporation of Mn on Zn sites rather than the formation of any metastable secondary phases [11]. Afterward Wang et al argued that exchange interaction between localized magnetic moments mediated by free charge carriers is responsible for Mn-doped ZnO film, and the increased charge carrier density should enhance the magnetic moment [12]. On one hand, the magnetism of Mn-doped ZnO is dramatically dependent on the preparation methods or experiment parameters.…”

Structure, optical and magnetic properties of (In1−Fe )2O3 films by magnetron sputtering

“…The exchange interaction gives rise to a negative and a positive correction to the energy of the conduction and valence bands, respectively. Namely, the conduction band is lowered and the valence band is raised leading to decreasing of the band gap [31]. The larger red-shift in the (In 1Àx Fe x ) 2 O 3 films with high Fe concentration also indicates a increasing sp-d exchange interaction.…”

Investigations on absorption, photoluminescence and magnetic properties of ZnO: Co nanoparticles

“…The magnetic behaviour of samples also affects the band gap of materials. The red shift in the band gap of DMS has been observed by some authors [35][36][37][38]. The ferromagnetism in cobalt-doped ZnO is due to localised magnetic moments mediated by free charge carriers.…”