Effects of high temperature annealing on single crystal ZnO and ZnO devices

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Authors

Mtangi, Wilbert
Auret, Francois Danie
Diale, M. (Mmantsae Moche)
Meyer, Walter Ernst
Chwanda, Albert
De Meyer, Hannes
Janse van Rensburg, Pieter Johan
Nel, Jacqueline Margot

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Volume Title

Publisher

American Institute of Physics

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.

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Keywords

High-temperature annealing, Single crystal ZnO, ZnO devices, Laplace DLTS, Current voltage

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Citation

Mtangi, W, Auret, FD, Diale, M, Meyer, WE & Chawanda, A 2012, 'Effects of high temperature annealing on single crystal ZnO and ZnO devices', Journal of Applied Physics, vol. 111, no. 8, pp. 084503-1-084503-6.