PUB-2017-ALD1

Atomic-Layer-Deposited SnO2 as Gate Electrode for Indium-Free Transparent Electronics

​​​Fwzah H. Alshammari, Mrinal K. Hota, Zhenwei Wang, Hala Al-jawhari, and Husam N. Alshareef "Atomic-Layer-Deposited SnO2 as Gate Electrode for Indium-Free Transparent Electronics"
​​Adv. Electron. Mater.​ D​OI: 10.1002/aelm.201700155​
Fwzah H. Alshammari, Mrinal K. Hota, Zhenwei Wang, Hala Al-jawhari, and Husam N. Alshareef
ALD tin dioxides, NMOS, ring oscillators, thin film transistors, transparent conducting oxides
2017
Atomic-layer-deposited SnO2 is used as a gate electrode to replace indium tin oxide (ITO) in thin-film transistors and circuits for the first time. The SnO2 films deposited at 200 °C show low electrical resistivity of ≈3.1 × 10−3 Ω cm with ≈93% transparency in most of the visible range of the electromagnetic spectrum. Thin-film transistors fabricated with SnO2 gates show excellent transistor properties including saturation mobility of 15.3 cm2 V−1 s−1, a low subthreshold swing of ≈130 mV dec−1, a high on/off ratio of ≈109, and an excellent electrical stability under constant-voltage stressing conditions to the gate terminal. Moreover, the SnO2-gated thin-film transistors show excellent electrical characteristics when used in electronic circuits such as negative channel metal oxide semiconductor (NMOS) inverters and ring oscillators. The NMOS inverters exhibit a low propagation stage delay of ≈150 ns with high DC voltage gain of ≈382. A high oscillation frequency of ≈303 kHz is obtained from the output sinusoidal signal of the 11-stage NMOS inverter-based ring oscillators. These results show that SnO2 can effectively replace ITO in transparent electronics and sensor applications.