本研究使用的NiCo2O4鎳鈷氧化物為一具尖晶石結構(spinel structure )[1]之P型半導體材料，具有低電阻率，且可應用在透明導電氧化物(Transparent Conducting Oxide, TCO) [2]上。
　　本研究利用硝酸鹽類配製鎳、鈷比例分別為莫耳比1 : 2，1 : 1與2 : 1之鎳鈷前驅物。鎳 : 鈷莫耳比為1 : 2時，以300˚C煅燒24小時後即可獲得NiCo2O4純相粉末。並觀察分別經由500˚C、1000˚C與1500˚C熱處理後對材料的結構之影響。將熱處理的溫度提高，NiCo2O4相比例逐漸減少；當熱處理溫度達到1000˚C以上，NiCo2O4相將全轉變為(Ni, Co)O岩鹽結構。
將此鎳 : 鈷莫耳比為1 : 2的前驅粉體以乾壓成型製成生胚，並以1500˚C燒結6小時後製備成靶材，在熱處理的升溫過程中，結構將由尖晶石結構轉變為(Ni, Co)O岩鹽結構。因此，本研究另分別利用較低溫度300˚C、400˚C、500˚C與600˚C對已相變之靶材進行熱處理，期望其能由(Ni, Co)O岩鹽結構轉為低溫穩定之NiCo2O4尖晶石結構。由實驗結果觀察到於600˚C熱處理12小時後，(Ni, Co)O岩鹽結構將開始相轉變為NiCo2O4，在600˚C熱處理時間達到120小時後，NiCo2O4相比例達58.6%，而將熱處理時間再延長至360個小時後，NiCo2O4相比例並沒有明顯的變化。
本研究使用此具(Ni, Co)O岩鹽結構的靶材分別於氬氣與氧氣下進行濺鍍製程，並由X-ray繞射分析觀察到濺鍍沈積薄膜之結構皆為非晶質，而將此初鍍膜以600˚C進行熱處理120小時後，將使得初鍍膜形成尖晶石結構之NiCo2O4，並使得濺鍍薄膜之電阻率降低；於氧氣氣氛下濺鍍之初鍍膜，並以氧氣氣氛進行熱處理120小時後，電阻率由4.21 x 10-1Ω.cm下降至5.41 x 10-2 Ω.cm。

NiO and CoO may react and form a low-resisitivity spinel structure with P-type conducting behavior and become one of transparent conducting oxides. In this study, nickel and cobalt nitrates with adequate ratio were mixed and heated at 300˚C for 24 h. Single-phase NiCo2O4 spinel was obtained. However, when the spinel powder were heated at temperatures 500˚C, 1000˚C, and 1500˚C, (Ni, Co)O solid solution with rock-salt structure appeared with consumption of NiCo2O4 spinel. At temperatures greater than 1000˚C, most spinel phases converted into the rock-salt phases.
To obtain a sputtering target consisting of nickel-cobalt oxides, the powder compact was sintered at 1500˚C for 6 h in air. Subsequently, low-temperature annealing was conducted to convert (Ni, Co)O with rock-salt structure into NiCo2O4 spinel. Spinel phase gradually appeared after annealing at adequate temperatures. For example, after annealing at 600˚C for 120 h, as high as 58.6% of (Ni, Co)O transformed to NiCo2O4 spinel.
To obtain a thin film of nickel-cobalt spinel, RF magnetron sputtering deposition method was adopted using (Ni, Co)O target under Ar or O2 atmosphere. The as-deposited film showed amorphous structure. With annealing at 600˚C for 120 h, a thin film of nickel-cobalt oxides showing spinel structure was obtained. The electrical property of spinel film was measured using 4-probe technique. The reduction in resistivity from 4.21 x 10-1Ω.cm down to 5.41 x 10-2 Ω.cm was observed.

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