Conversion of insulating thin films of MgIn2O4 into transparent conductors by ion implantation

MgIn2O4 (IMO) is a crystal with spinel-type structure and has a wide band gap of similar to 3.5 eV. Electrical conductivities in rf sputter-deposited thin films of IMO at room temperature increased from <10(-7) to similar to 10 S . cm(-1) (n-type conduction) in the as-implanted state, when implanted with H+ or Li+ to a fluence of 2x10(16) cm(-2). The efficiency of carrier generation was similar to 20% in the as-implanted state and similar to 40% after annealing at 300 degrees C for H+ and Li+, respectively. No carrier generation was perceived in He+-implanted specimens. Although color centers, giving a band at similar to 500 nm, were produced by implantation, they disappeared during annealing at similar to 300 degrees C. As a consequence, optically transparent conducting IMO films were obtained by implantation and subsequent annealing.