AbstractAcousto-electric current saturation has been observed in thin, polycrystalline Al-doped zinc oxide films grown on fused quartz. The films, grown by laser ablation, are c-axis textured with high angle grain boundaries between the grains. After annealing at 600°C in 0.1 mtorr oxygen, the films exhibit a current saturation at a current density of 2 105 A/cm2 and electric fields of 5 103 V/cm. However, under constant field the current density falls and the current saturation behavior is not maintained. Current saturation at the same current density can, however, be restored by increasing the electric field. Similarly, the appearance and disappearance of the current saturation behavior can be reversibly controlled by annealing in different oxygen partial pressures at 200°C. The degradation phenomena is attributed to the high acoustic flux enhancing the diffusion of oxygen along the grain boundaries where oxygen can alter the grain boundary potential barrier and hence the electric field in the grains.
Optical quality zinc oxide films have been characterized using
reflection electron diffraction (RED), replication electron microscopy
(REM), scanning electron microscopy (SEM), and X-ray diffraction (XRD).
Significant microstructural differences were observed between rf sputtered
films and planar magnetron rf sputtered films.
Piezoelectric materials have been attractive for applications to
integrated optics since they provide an active medium for signal processing.
Among the desirable physical characteristics of sputtered ZnO films used for
this and related applications are a highly preferred crystallographic
texture and relatively smooth surfaces. It has been found that these
characteristics are very sensitive to the type and condition of the
substrate and to the several sputtering parameters: target, rf power, gas
composition and substrate temperature.
Observation and simulation of hard x ray photoelectron diffraction to determine polarity of polycrystalline zinc oxide films with rotation domains