Abstract:
We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO
devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS
measurements. Current–voltage measurements reveal the decrease in the quality of devices fabricated
on the annealed samples, with the high-temperature annealed samples yielding devices with low
barrier heights and high reverse currents. DLTS results indicate the presence of three prominent
defects in the as-received samples. Annealing the ZnO samples at 300 C, 500 C, and 600 C in Ar
results in an increase in reverse leakage current of the Schottky contacts and an introduction of a new
broad peak. After 700 C annealing, the broad peak is no longer present, but a new defect with an
activation enthalpy of 0.18 eV is observed. Further annealing of the samples in oxygen after Ar
annealing causes an increase in intensity of the broad peak. High-resolution Laplace DLTS has been
successfully employed to resolve the closely spaced energy levels.
