Fabrication of single crystal field-effect transistors with phenacene-type molecules and their excellent transistor characteristics

• Fabrication of field-effect transistors with single crystals of new phenacene molecules.
• Achievement of high field-effect mobility and low voltage operation in single crystal field-effect transistors.
• Interface modification with electron-acceptor molecules to improve the transistor performance.

Single crystal field-effect transistors (FETs) using [6]phenacene and [7]phenacene show p-channel FET characteristics. Field-effect mobilities, μs, as high as 5.6 × 10−1 cm2 V−1 s−1 in a [6]phenacene single crystal FET with an SiO2 gate dielectric and 2.3 cm2 V−1 s−1 in a [7]phenacene single crystal FET were recorded. In these FETs, 7,7,8,8-tetracyanoquinodimethane (TCNQ) was inserted between the Au source/drain electrodes and the single crystal to reduce hole-injection barrier heights. The μ reached 3.2 cm2 V−1 s−1 in the [7]phenacene single crystal FET with a Ta2O5 gate dielectric, and a low absolute threshold voltage |VTH| (6.3 V) was observed. Insertion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) in the interface produced very a high μ value (4.7–6.7 cm2 V−1 s−1) in the [7]phenacene single crystal FET, indicating that F4TCNQ was better for interface modification than TCNQ. A single crystal electric double-layer FET provided μ as high as 3.8 × 10−1 cm2 V−1 s−1 and |VTH| as low as 2.3 V. These results indicate that [6]phenacene and [7]phenacene are promising materials for future practical FET devices, and in addition we suggest that such devices might also provide a research tool to investigate a material’s potential as a superconductor and a possible new way to produce the superconducting state.

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