Carrier control in transparent semiconducting oxide thin films by ion implantation:: MgIn2O4 and ZnO

Thin films of MgIn2O4 and ZnO were prepared by pulsed laser deposition technique. HI implantation into insulating MgIn2O4 films was carried out to generate carrier electrons. Upon implantation of 5 x 10(16) cm(-2), DC conductivity at 300 K increased from below similar to10(-7) to similar to70 Scm(-1). Hot implantation at 500 degreesC resulted in a further increase in the conductivity to similar to500 Scm(-1). Hall voltage measurements revealed that the further increase in the conductivity by hot implantation originates from the enhancement of carrier generation efficiency. Hole doping by N+ implantation into n-type Ga-doped ZnO (ZnO:Ga) thin films was attempted to realize p-type ZnO films under Ga + N co-doping scheme proposed by Yamamoto and Yoshida. The conductivities monotonously decreased from 8.2 x 10(2) to 2.7 x 10(-5) Scm(-1) with increasing N+-fluences, indicating holes generated by N+ implantation compensated already existing electrons in the ZnO:Ga films. However, conduction type inversion (n --> p) was not observed irrespective of implantation conditions. (C) 2002 Published by Elsevier Science B.V.