Development of room temperature spin polarised emitters

The mechanism leading to RT ferromagnetism in Gd-doped GaN is not well understood. Oxygen impurities have been proposed as a possible contributor to ferromagnetic behavior in Ga_1-xGd_xN films but the physical mechanism is not clear. In this work, Ga_1-xGd_xN thin films were grown by MOCVD using two different metalorganic Gd precursors (TMHD)₃Gd and Cp₃Gd. Samples grown with (TMHD)₃Gd, which contains oxygen, exhibited much higher magnetic moments. Co-doping of the Ga_1-xGd_xN films with Si produced conductive n-type material, while co-doping with Mg produced compensated p-type material. Si and Mg co-doped films exhibited room temperature ferromagnetism and this material was then incorporated into a room temperature spin-polarized LED. Electroluminescence from this device had a degree of polarization of 14.6% at 5000 Gauss and retained a degree of polarization of 9.3% after removal of the applied magnetic field.