Using current-voltage (I-V) and capacitance-voltage (C-V) measurements, the effect of oxygen plasma treatment on the electrical properties of Ag Schottky contacts to hydrothermally-grown O-polar bulk ZnO was investigated. Schottky contacts to untreated ZnO had higher barrier heights and lower ideality factors than those to oxygen plasma treated ZnO. The measured C-V and conductance-voltage (G/ω-V) characteristics for both samples showed strong dependences on bias voltage and frequency. The increments of series resistance in small forward bias region (0-0.5 V) was larger for oxygen plasma treated ZnO, indicating that the contribution of interface states to series resistance was more significant. The interface state density was obtained from the corrected C-V and G/ω-V characteristics with considering series resistance. The higher interface state density was found for oxygen plasma treated ZnO, implying that oxygen plasma induced the interface states near the ZnO surface.
Bibliographical noteFunding Information:
This work was supported in part by the IT R&D program of the Ministry of Knowledge Economy/Korea Evaluation Institute of Industry Technology (MKE/KEIT) [10040379, Development of 5W Full Color (R, G, B) Laser Diodes & Modules for Convergence Appliances].
- Interface state density
- O-Polar bulk ZnO
- Oxygen plasma