11:30 〜 11:45
▼ [12a-D419-10] Electric Field Thermopower Modulation Analyses of the Operation Mechanism of Amorphous SnO2 Thin Film Transistor
キーワード：Transparent thin film transistor, Amorphous SnO2, Electric field thermopower modulation
Currently, amorphous (a-) InGaZnO4 is widely applied as the TAOS of the TFT channel of the commercially available OLED displays with a μFE is ~10 cm2 V−1 s−1[1]. Among TAOSs, a-SnO2 has several advantages against current a-InGaZnO4 such as higher μFE >100 cm2 V–1 s–1[2], which is one order of magnitude higher than that of a-InGaZnO4 and indium free. Although there are several researches on a-SnO2 TTFT, the operation mechanism has not been clarified thus far due to the strong gas sensing characteristics of SnO2.
We prepared a bottom-gate top-contact type TTFT by pulsed laser deposition technique using 4.2-nm-thick a-SnO2 as the channel without any surface passivation. We measured the transistor characteristics and thermopower(S) in air and vacuum. The resultant a-SnO2 TTFT showed clear transfer (Id–Vg) characteristics with the on-to-off current ratios of ~105. All the TFTs show clear pinch-off in the output characteristics. The threshold voltage (Vth) was −14.7 V in air whereas it shifted dramatically to −25.25 V in vacuum shows a strong gas sensing characteristic. The teff ≡ ns/n3D of the conducting a-SnO2 channel were always ~1.0 ±0.4 nm, insensitive to the gas atmosphere. From the thickness of the a-SnO2 film (4.2 nm) and the teff (1.0 ±0.4 nm), the carrier depletion depth at the top surface was concluded to be 3 nm of the a-SnO2 film, which shows the similar depletion length as reported data.
We prepared a bottom-gate top-contact type TTFT by pulsed laser deposition technique using 4.2-nm-thick a-SnO2 as the channel without any surface passivation. We measured the transistor characteristics and thermopower(S) in air and vacuum. The resultant a-SnO2 TTFT showed clear transfer (Id–Vg) characteristics with the on-to-off current ratios of ~105. All the TFTs show clear pinch-off in the output characteristics. The threshold voltage (Vth) was −14.7 V in air whereas it shifted dramatically to −25.25 V in vacuum shows a strong gas sensing characteristic. The teff ≡ ns/n3D of the conducting a-SnO2 channel were always ~1.0 ±0.4 nm, insensitive to the gas atmosphere. From the thickness of the a-SnO2 film (4.2 nm) and the teff (1.0 ±0.4 nm), the carrier depletion depth at the top surface was concluded to be 3 nm of the a-SnO2 film, which shows the similar depletion length as reported data.