脈衝雷射蒸鍍法製備氧化鉺薄膜的探討:結構、光學與磁性研究

Abstract

利用脈衝雷射沉積法製備摻雜鉺的氧化鋅薄膜，在3×〖10〗^(-1)及3×〖10〗^(-3)mbar兩氧壓下用蓋板法與銀膠法固定基板加熱。XPS成分分析利用Er離子面積計算薄膜比例與靶材比例相近。X光繞射譜中，摻雜Er濃度越高，在低氧壓下兩製備法的 ZnO結晶品質越差且c軸晶格常數越大，而高氧壓下兩制備法的ZnO結晶品質越差且c軸晶格常數先變小在變大。蓋板法在不同氧壓下製備氧化鉺鋅薄膜，高氧壓下薄膜整體結晶品質比低氧壓佳。 拉曼光譜中，低氧壓只有蓋板法可觀察到ZnO的E_2 (high)及E_2 (low)的振動模式;高氧壓下兩製備方法皆有ZnO E_2(low)且ZnO有強烈E_2(high)訊號，Er 3at.%螢光效應最強。PL光譜顯示近能隙發光強度隨著Er濃度上升而下降，缺陷發光則隨Er濃度上升而增加，低氧壓PL光譜由近能隙、鋅空缺、鋅間隙所貢獻，高氧壓PL光譜由近能隙、鋅空缺、鋅間隙、氧空缺、氧間隙所貢獻。SQUID m-H圖顯示室溫ZnO無磁性，其他濃度氧化鉺鋅薄膜為順磁性，而低溫氧化鉺鋅薄膜為順磁性。

Pulsed-laser deposition (PLD) was applied to grow erbium(Er)-doped ZnO thin films on c-sapphire substrate under two different oxygen pressures : 3×〖10〗^(-3) and 3×〖10〗^(-1) mbar by using shadow mask or silver glue. XPS analysis showed Er/Zn ratio of target was close to thin film which was calculated by using Er ion area. X-ray diffraction spectrum showed decreasing crystal quality of ZnO and increasing c-axis lattice constant with increasing Er doping concentration in two oxygen pressures for both methods. The overall crystal quality of Er-doped ZnO films in high oxygen pressure were better than in low oxygen pressure for shadow mask method. Raman spectroscopy only observed ZnO vibrational modes E_2(high) and E_2(low) in low oxygen pressure for shadow mask method. All films have E_2(low) and ZnO have stronger E_2(high) for two method in high oxygen pressure, however above Er 3at.%, fluorescent effect was observed for all films. PL spectra show near band gap(NBE) emission intensity decreased and defect luminescence emission(DLE) intensity increased with Er concentration increased . PL spectra emission consisted of near band gap(NBE), zinc vacancies and zinc interstitials in low oxygen pressure, however whose consisted of near band gap(NBE), zinc vacancies, zinc interstitials, oxygen vacancies, oxygen interstitials in high oxygen pressure. Magnetic investigations by SQUID showed no magnetism for pure ZnO thin film and paramagnetism for Er-doped ZnO thin films at T=300K and T=5K.