將氧化鋅成長在砷化鎵基板上的結構、光學及電性探討

Abstract

我們成功的將高品質氧化鋅薄膜以雷射濺鍍方法磊晶成長於不同極性的(111)面砷化鎵基板上，利用Ｘ光繞射可以得知樣品在垂直表面方向的磊晶結構關係為氧化鋅 (002)[210] // 砷化鎵(111)[-1-12]。由霍爾量測可以得知在退火前樣品的電性是屬於N型半導體，當退火在600°C時，氧化鋅的電性會從N型轉換成P型半導體，這個原因主要是因為砷和鎵從基板擴散進到氧化鋅薄膜中。我們也利用螢光光譜來量測樣品的光學特性，從螢光光譜，可以得知能隙發光的位置改變暗示著電性上的轉變。從Ｘ光電子能譜和能量散佈分析儀可以得知砷和鋅鍵結在電性上將提供電洞，這是由於鎵元素摻雜到氧化鋅薄膜中將形成複合物，進而提供電洞，可以由此來解釋電性上之變化。

We have successfully grown wurtzite ZnO epitaxial layers on various substrates, including GaAs(111)A, and GaAs(111)B by pulsed laser deposition (PLD). Structural investigation by X-ray diffraction reveals good crystalline quality and the epitaxial relationship is ZnO (002)[210] || GaAs (111)[-1-12]. Hall effect measurements indicate that the as-deposited samples are n-type in character. After annealing at 600°C, the electric properties of the ZnO have converted into to p-type. It is attributed to the arsenic and gallium diffusion from the substrate. In addition, the optical properties of the samples were characterized by low temperature photoluminescence (PL) measurement. Peak of near band edge (NBE) shifting suggests that the increase of hole concentration overcomes the electron concentration. Finally, results of the XPS and EDS measurements tell us that the As-Zn can supply holes in electricity, and Ga doping complexes can be to provide the acceptor, which explain the conductivity measurements in ZnO film.