Development of the field-effect mobility in thin films of F16PcCu characterized by electrical in situ measurements during device preparation

作者：Keil C; Schlettwein D^*

来源：Organic Electronics, 2011, 12(8): 1376-1382.

DOI：10.1016/j.orgel.2011.04.016

• Organic field effect transistor
• Phthalocyanine
• Film growth
• In situ analysis
• Electron mobility
• Threshold voltage

Films of F16PcCu prepared by physical vapor deposition under high vacuum conditions were characterized from the monolayer range up to 40 nm thickness. The charge carrier mobility in the saturation regime of the output characteristics and the threshold voltage as well as the on/off-ratio were determined during film preparation. The substrate consisted of a n(++)-doped Si wafer as gate electrode with a thermally grown SiO2 layer as gate dielectric and photolithographically structured films of gold or silver as source and drain electrodes. F16PcCu formed a conductive channel in the interface region at about 2 nm average film thickness. In the subsequent regime of layer formation up to about 8 nm a constant charge carrier mobility was established. The threshold voltage considerably decreased during this period of growth and reached a stable level. Subsequent island formation on top of this channel led to only minor changes in the transistor characteristics although the conductivity along the complete organic thin film decreased considerably. By such in situ characterization different contributions of interfacial and bulk transport could be determined and used to optimize films to be used in organic field effect transistors. Ultrathin films of F16PcCu further showed a considerably faster stabilization of the mobility upon exposure to air, the highest on/off ratios and therefore provide clear advantages for device applications.

• 出版日期2011-8