Band-gap tailoring of ZnO by means of heavy Al doping

Films of ZnO:Al were produced by weakly reactive dual-target magnetron sputtering. Optical band gaps, evaluated from spectrophotometric data, were widened in proportion to the Al doping.The widening could be quantitatively reconciled with an effective-mass model for n-doped semiconductors, provided the polar character of ZnO was accounted for.