Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: ZnO: Devices

HL 48.12: Vortrag

Mittwoch, 16. März 2011, 13:15–13:30, POT 151

Trap-related behavior of charge carrier transport in transparent conductive oxides — •Marlis Ortel and Veit Wagner — School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

Recently significant progress was made in the field of wet-chemically processed metal oxide semiconductors. Even though these materials are amorphous they show high mobility values of up to 100 cm2/Vs. Furthermore metal oxide semiconductors are transparent due to their large band gap. The combination of both properties makes these materials important for applications such as transparent electronics.

However TCO-based devices often show hysteresis and stress-related threshold voltage shift, which is not acceptable in many applications. In this work the charge carrier transport in TCO-based transistors is analyzed. The semiconductor is wet-chemically deposited from a precursor solution and thermally converted into ZnO. The hysteresis and bias stress in these layers are attributed to trapping of charges. The observed threshold voltage shifts are strongly affected by charge carrier density, electric field strength, temperatures and ambient gases. To gain detailed information about the local threshold voltage shift within the channel is obtained via 4-probe setup. This setup includes two electrodes in the conducting channel which enable the determination of the potential in the channel while stressing the device and thus yield valuable information if charge density or electric field strength is more important. The analysis yields, among others, especially a strong influence of the electric field strength on the observed bias stress.