Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.42: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

Temperature Dependent Bias-Stress Effects on in-situ OFET Characteristics — •B. Gburek, M. Michelfeit, M. Leufgen, G. Schmidt, J. Geurts, and L.W. Molenkamp — Universität Würzburg, Physikalisches Institut (EP III), Am Hubland, D-97074 Würzburg, Germany

It is well known that applying external voltages to an organic field effect transistor (OFET) quickly results in a performance degradation. To examine this effect more closely we fabricated OFETs with dihexylquaterthiophene (DH4T) as active material by organic molecular beam deposition in UHV and characterised their electrical properties in situ. Therefore, we applied constant gate/source and/or drain/source voltages V = ± 15 V. Besides the time of their application, we also varied the sample temperature between 150 and 360 Kelvin. Upon application of a negative gate and drain bias, a clear shift of the threshold voltage towards higher negative values was observed, strongly increasing with temperature. This shift was reversible, showing nearly full relaxation after a few minutes. The relaxation was enhanced by the application of a positive gate bias. While the charge carrier mobility remained unaffected at room temperature, the simultaneous application of gate/source and drain/source voltage at elevated temperatures induced a mobility increase beyond 50 percent. This effect also showed full reversibility.