20120202

Nano Functional Ceramic Lab.

•前言

•實驗步驟

•結果與討論

•結論

•未來工作

Outline

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前言

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· Recently, a variety of onedimensional (1D) nanostructures including nanowires, nanorods, nanobelts, nanosprings and nanorings have been produced.

· These 1D nanostructures show very high surface-to-volume ratios and great surface activities, which could translate to better gas response and selectivity properties in terms of chemical sensing.

· As an n-type semiconductor, SnO2 has been extensively exploited in applications related to gas sensing.

· Recently, a hybrid structure of SnO2 nanorod thin films consisting of Q1D SnO2 nanorods embedded in a 2D SnO2 thin film matrix. The SnO2 nanorod thin film exhibited better sensing properties with faster response and shorter recovery time at lower operating temperatures.

· In this paper, single SnO2 nanorod gas sensors have been fabricated by a focused ion beam (FIB). The sensing properties of the single SnO2 nanorod sensors towards H2 gas were studied.

實驗步驟

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Precursor : (C4H9)2Sn(OOCCH3)2 二醋酸二丁基錫

The precursor vapor was carried into the deposition chamber by argon

The wafer was inserted in a quartz boat perpendicularly. Oxygen was used as the reaction gas.

· No catalyst and additional substrate heating during deposition was performed.

· 製備 SnO2 nanorod

Substrate : A 4 inch SiO2/Si wafer

實驗步驟

· 製備 SnO2 single-nanorod gas sensors

首先，把先前在 SiO2/Si wafer 上生成的的 SnO2 nanorod 刮下來

放進乙醇中，以超音波震盪分散

The Au/Ti electrodes (Au/Ti = 300/20 nm) were deposited on the SiO2/Si wafer by e-beam evaporation

利用微球管，把 SnO2 nanorod suspension 滴在兩端電極中央，會形成一個電場，以 AC dielectrophoresis (5V, 1MHz) ， until the

suspension completely dried out.

The SnO2 single-nanorod gas sensors were fabricated by connecting individual SnO2 nanorods to a pair of Au/Ti electrodes with Pt stripes deposited by focused ion beam.

XRD SEM TEM I-V curve

And were patterned by standard UV lithographic and liftoff processes.

liftoff processes:剝離製程，為一種常見的金屬圖案成形法。

實驗步驟

· Gas sensing

參考氣體 : Air

帶測氣體 : H2 , 100 ppm (dry air with total flow of 500 sccm)

溫度 : 25 ℃ , 200 , 25 ~350 ℃ ℃ ℃

Response: R air

R H2