氧硫化鋅合金薄膜的結構與光學特性之研究

Structural and Optical Properties of ZnS1-xOx Thin Films

游宗樺(Tsung-Hua You)

指導教授 ： 洪魏寬

國立臺北科技大學/機電學院/光電工程系所/碩士(2007年)

摘要

我們利用脈衝雷射蒸鍍法(pulsed laser deposition,PLD)的方式，蒸鍍ZnS靶材和不同的氧壓去合成一連串全範圍0≦x≦1的等價Ⅱ-Ⅵ族ZnS1-xOx合金。在結構方面，利用X光繞射觀察到ZnS(0002)繞射峰值會隨不同的氧壓位移到ZnO(0002)繞射峰值，表示O原子有漸漸完全取代同為陰離子的S原子。以穿透光譜量測的結果轉為吸收係數平方比光子能量，去決定出能隙大小，結果呈現因有大的晶格不匹配與電負性差異所以在不同的成分比(x)下能隙會產生彎曲的現象。利用拉曼光譜的觀察因磊晶層內合金產生的錯位使得有拉曼位移的現象，量測發現ZnS-like的LO和ZnO-like的LO的兩個模態各會產生直線的位移與彎曲位移。

關鍵字

脈衝雷射蒸鍍法 ； 合金 ； 氧硫化鋅

並列摘要

In this thesis, the structural and optical properties of epitaxial ZnS1-xOx (0 < x < 1) alloy grown on c-plane sapphire substrates by pulsed laser deposition were investigated. A ZnS target was laser ablated in an oxygen atmosphere to form the ZnSO film on the substrate. X-ray diffraction measurements revealed that the crystalline properties and the composition of the alloy strongly depend on the substrate temperature. Lower growth temperature favors higher incorporated oxygen content. The (0002) reflection peak shifts continuously from the ZnS value to the ZnO value by increasing the O2 partial pressure, indicating the alloy ZnS1-xOx of almost complete composition range was successfully synthesized. The absorption coefficients retrieved from optical transmission measurements were used to determine the band gap energies. Large band gap bowing coefficient, usually observed in highly mismatched semiconductor alloys, was determined to be approximately 2.8 eV. Furthermore, the Raman spectra for ZnS1-xOx were also investigated. The lattice vibration showed two-mode behavior. It was found that the ZnS-like LO phonon peak showed a slight blueshift with increasing O composition x. However, the composition dependence of the ZnO-like LO phonon peak showed a strange bowing behavior, which calls for further detailed experimental and theoretical studies.

並列關鍵字

PLD ； alloys ； ZnSO

參考文獻

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