以反應性濺鍍成長P型氧化亞銅薄膜特性於太陽能電池上應用之研究

The Properties of P-type Cuprous oxide films prepared by reactive sputtering in solar cells application

楊程凱(Cheng-Kai Yang)

指導教授 ： 林天財

共同指導教授 ： 張慎周(Shang-Chou Chang)

崑山科技大學/工程學院/電機工程研究所/碩士(2009年)

摘要

氧化亞銅是p-type 直接能隙半導體材料，其能帶間隙約為2eV，由於材料的優點，使得氧化亞銅在光電設備與化學催化劑的應用上引起相當大的注意。因具有低成本、無毒性、自然界含量豐富，在可見光有很好的光吸收特性、並可利用各種鍍膜法來沉積薄膜，製程簡單且成本低廉等優點，於是了解氧化亞銅材料特性，可以更加改善太陽能電池的效能與其應用。
　　本研究利用射頻磁控濺鍍系統，使用銅靶進行反應性濺鍍備製氧化亞銅薄膜，改變不同的射頻功率及製程溫度，探討氧化亞銅薄膜之特性。此外，在基板側施加直流偏壓，進行基板偏壓製程，探討不同直流偏壓，對氧化亞銅薄膜特性的影響。本實驗也利用高溫爐管，對氧化亞銅薄膜進行退火處理，以不同處理溫度與時間，探討其特性變化。並以n-AZO 與p-Cu2O 兩種材料，以不同堆疊方式，探討對太陽能電池元件特性之影響。實驗以α-step 量測鍍膜厚度、四點探針及霍爾量測儀量測鍍膜電阻率、X-ray 繞射進行薄膜結構分析、SEM 觀察其表面形貌、UV-VIS 量測光穿透率、I-V 量測元件之特性。
　　實驗結果顯示，純相的氧化亞銅成長條件不易控制。當製程溫度250℃，射頻功率160W，當氧氣流量為0.7sccm，製程壓力在5mtorr~7mtorr 可得到純Cu2O相。另外，在功率175W，可得最低電阻率為6Ω-cm。基板偏壓會改變薄膜成長機制，結晶方向會隨著基板偏壓而有不同。另外太陽能電池元件的部分，n-AZO與p-Cu2O 不同的成長順序對於元件特性有很大的影響，將p-Cu2O 成長於n-AZO上的異質接面，其所製作出的元件則有較好的二極體特性曲線。

關鍵字

氧化亞銅 ； 反應性濺鍍

並列摘要

Cuprous oxide (Cu2O) is a direct band gap and is p-type semiconductor with a direct band gap of 2.0 eV, and has been attracted to apply in photoelectric devices and chemical catalysis. Cu2O is considered to be an attractive material since it has the advantages of non-toxicity, high absorption coefficient and low-cost producibility. To understand Cu2O characteristics can provide useful and fundamental datum to promote the efficiency of solar cells.
The effects of Cu2O thin films deposited by reactive radio-frequency magnetron sputtering were studied. Cu was used as the sputtering target. The RF power and the temperature was changed in order to obtain a cuprous oxide film with different characteristics. The influence of films growing characteristics depended on bias voltage was also discussed. In addition, annealing treatment was used to improve electric properties. In the solar cells parts, we use n-AZO and p-Cu2O films to stack different structure, discusses the cells characteristics of various structure. An α-step equipment was used to detect film thicknesses. A 4-points probe was used to measure the sheet resistivity and Hall measurement was used to detect the carrier concentration and mobility. The structure could be characterized by X-ray diffraction (XRD).The iv surface morphologies were observed by SEM. The transmittance was measured by UV-VIS spectrophotometer. I-V measurement was used to analyzed the I-V curve.
The experimental results show that the region grow a single phases of Cu2O films was not easy to control. When process parameters were set at 250℃, the rf power of 160W, the oxygen flow rate of 0.7sccm and the work pressure changed from 5~7mtorr, a single phase of Cu2O films can be obtained. At rf power of 175W, the lowest resistivity of 6Ω-cm, were obtained. The preferred orientation and surface morphologies were significantly changed with bias voltages, therefore, the results show the growth mechanism was also closely relative to bias voltages. The different stacking sequence of n-AZO and p-Cu2O solar cells show a large influence of I-V curve. The device of p-Cu2O on n-AZO to form heterojunction has better characteristic of I-V curve.

並列關鍵字

Cuprous oxide ； reactive sputtering

參考文獻

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