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We studied the Hall-effect mobility of pentacene films prepared by the thermal evaporating method with different substrate temperature. A crossover from coherent bandlike charge transport with mobilities up to several tens of cm 2 /V-s at low temperature to an incoherent hopping motion at high temperature is observed. The carrier mobilities of pentacene exhibit a hopping-to-band transition around room temperature. An exhibition of high mobility of pentacene films prepared with substrate temperature of 90 C is attributed to the increased spacing between molecules.

The fabrication of memory devices based on the Au/pentacene/heavily doped n-type Si (n+-Si), Au/pentacene/Si nanowires (SiNWs)/n+-Si, and Au/pentacene/H2O2-treated SiNWs/n+-Si structures and their resistive switching characteristics were reported. A pentacene memory structure using SiNW arrays as charge storage nodes was demonstrated. The Au/pentacene/SiNWs/n+-Si devices show hysteresis behavior. H2O2 treatment may lead to the hysteresis degradation. However, no hysteresis-type current-voltage characteristics were observed for Au/pentacene/n+-Si devices, indicating that the resistive switching characteristic is sensitive to SiNWs and the charge trapping effect originates from SiNWs. The concept of nanowires within the organic layer opens a promising direction for organic memory devices.

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