High-mobility pentacene thin-film phototransistor with poly-4-vinylphenol gate dielectric

✍ Scribed by Jae-Hong Kwon; Myung-Ho Chung; Tae-Yeon Oh; Hyeon-Seok Bae; Jung-Ho Park; Byeong-Kwon Ju; Fahrettin Yakuphanoglu

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 706 KB
• Volume: 156
• Category: Article
• ISSN: 0924-4247
• DOI: 10.1016/j.sna.2009.10.011

✦ Synopsis

An organic thin-film transistor was fabricated with pentacene as the active material and poly(4-vinyl phenol) as the gate-dielectric material. Atomic force microscope image shows that the pentacene film grows in the polycrystalline structure of the poly-4-vinylphenol (PVP) dielectric layer with the surface root-mean square (RMS) roughness of 6.0 nm and average grain size of 800 nm. The pentacene thinfilm transistor exhibited a saturation field-effect mobility of 1.64 cm 2 /V s, a threshold voltage of -18 V, a sub-threshold swing of 3.53 V/decade, on/off-current ratio of 7.1 × 10 4 and interface trap density of 5.39 × 10 12 eV -1 cm -2 . The higher mobility of pentacene on poly(4-vinyl phenol) layer is attributed to the larger grain size of the pentacene. The photoresponsive properties of the organic thin-film transistor were investigated under various illumination intensities. The photosensitivity was measured as 1.46 at an illumination intensity of 100 mW/cm 2 at the off state. This suggests that the pentacene thin-film transistor shows a phototransistor behavior.