氧化鏑鋅薄膜的法拉第磁光與電性

Abstract

以脈衝雷射蒸鍍法在c方向藍寶石基板上製備氧化鏑鋅薄膜，並討論其結構、光學、磁光與電性特性。分析X光繞射光譜與拉曼光譜，並沒有產生其他晶相，隨摻雜濃度增加，晶粒尺寸變小，晶格常數變化不大。光致螢光光譜顯示，純氧化鋅有很強的近能隙發光，隨摻雜濃度增加，近能隙發光強度漸弱，缺陷發強度增強，主要缺陷為氧空缺、鋅空缺與鋅間隙。磁光光譜可看出，所有薄膜呈順磁性，與SQUID量測結果相同，Verdet constant大致隨波長增長而漸弱；其中缺陷所對應的發光波長，Verdet constant 與摻雜比例做圖，摻雜濃度10%響應為最強。量測電流-電壓曲線圖得知所有電極都為歐姆接觸。使用Van der Pauw法量測氧化鏑鋅薄膜的電阻率數值在0.078 mΩ·cm與277.72 mΩ·cm之間。霍爾效應檢測顯示氧化鋅為n型半導體，1%及5%的氧化鏑鋅薄膜為p型半導體，載子濃度在7.89×1018 cm-3與5.32×1022 cm-3之間，遷移率在4.3×10-4 cm2/Vs與35.13 cm2/Vs之間。Dysprosium-doped zinc oxide (Dy:ZnO) thin films are grown by pulsed-laser deposition on c-oriented sapphire substrate and their structural, optical, magneto-optical, and electrical properties at room temperature are discussed. The x-ray diffraction and Raman scattering analysis confirm the wurtzite structure of ZnO without secondary phase. With the Dy dopant concentration increasing, grain size becomes smaller while c-lattice constant does not change much. In photoluminescence spectra, ZnO shows strong near band edge (NBE) emission. The NBE luminous intensity decreases and the defect intensity increases when Dy concentration increases. The main defects are oxygen vacancy (VO), zinc vacancy (VZn) and zinc interstitial (Zni). Study of the magneto-optical Faraday effect spectra shows that all the thin films are paramagnetic, which is the same from SQUID measurement. Verdet constant of Dy:ZnO thin films decrease with increasing wavelength. When analyzing the spectra of defects, take the zinc interstitial as an example, the Verdet constant becomes larger with an increase of Dy concentration. I-V curves show all Dy:ZnO thin films having ohmic contact. Van der Pauw method was used to measure the resistivity of Dy:ZnO thin films and the values are between 0.078 mΩ·cm and 277.72 mΩ·cm. Hall effect measurements shows that pure ZnO thin film is an n-type semiconductor, and Dy:ZnO thin films with 1 and 5 at.% are p-type semiconductors. The carrier density is between 7.89×1018 cm-3 and 5.3×1022 cm-3, and the mobility is between 4.3×10-4 cm2/Vs and 35.15 cm2/Vs.